I stopped tipping smug, arrogant, counter workers years ago.
I never understood the whole concept of tipping BEFORE you receive service and/or product that you are paying for. Nothing worse than providing a generous tip up front, only to be disappointed with bad service or bad product. Can I have my tip back please?
There is a deli near my house where this is a prime example. They make some of the most amazing sandwiches ever. However, their staff is smug, arrogant, slow, and most of the time, downright rude. They almost expect a tip up front when you pay. The last time I was there, it took them almost 30 minutes to make a sandwich. And no, the place wasn't busy nor were they understaffed. They just decided to take their sweet time.
And when questioned about the time it took to make a sandwich (very politely, mind you), I received an eye-roll, followed by the employee just turning around and walking away.
I was a server for my entire college life, now I'm a mom, in a few different cities and their suburbs. I've definitely gotten some really bad service here. And after having worked the business I know both sides.
So, I no longer tip up front.
Skip the "thank you" and skip the restaurant in the future. When I go out to eat I am polite but I am paying for service. That means I am not putting anyone out. This is their job, their livelihood. And I expect service. Nothing out of the ordinary, but service none the less.
Recently we requested the private wine room because we had a toddler with us and didn't want to disturb the other patrons. The owner kept on turning off the air conditioning because he was sitting under a vent drinking at the bar. So we propped open the door. He yelled at us that the kid was being disruptive (she wasn't) and slammed the door closed. He also said he wouldn't turn the air on because he didn't give a rats ass about the temperature in the wine room.
Around dessert he peaks his head in again and VERY obviously drunk told us the baby had to leave and we couldn't return.
Ok so... obviously we go there still but we steered clear for awhile and my dad called in a significant invoice.
The kicker is that he has done this to other patrons as well. He gets so wasted he can hardly talk then kicks out children of paying customers. This is a fairly nice restaurant. The food is good. When people come with their families the kids are well behaved. It's a dress up a bit kind of place.
Anyway, he acted like a jerk, and yet I keep ordering $90 bottles of wine when I go.
Saying thank you isn't at all deferential so I would say it's a different situation. Generally speaking, if someone seems to never thank people (and as you said, may in fact be thankful) that's probably just a factor of their being somewhat inconsiderate. Perhaps they have poor "theory of mind" and thus can't understand why it's a nice thing to do, or maybe they simply never learned that thanking people is a socially proper thing to do, etc.
Apologizing is much more interesting. There have been a number of studies about the act of apology or otherwise "admitting to error." For instance that people are more likely to trust those who are able to apologize or own up to mistakes (be they personal or occupational or etc.). Which I guess just makes sense.
Here is a good article on "Sorry". Basically, self-serving cognitive biases involved.
Now "Thank you", I'd guess, is pretty simple. When you're thanking someone for something, that means that you are verbally acknowledging the person did some favor/kindness for you. Then, with the principle of social reciprocity involved, that means you acknowledging yourself now being obliged to do a favor for this person in future. And naturally humans REALLY don't like to be anyhow indebted. So, not saying "thanks" is just a silly unconscious try to avoid being indebt.
All people can have trouble apologizing.
The conflict that created the apology and people's ability to conceptualize it play a huge part. I assume what you're asking is why some people have trouble even when they are blatantly wrong. Of course it's tied to self-esteem/pride, that's only obvious. People who are particularly narcissistic will often skew events in their heads to support themselves. However even someone thinking clearly, faced with the indignation of "losing" and the angry emotional state of an argument, may falter or avoid apology.
It requires a security in both the self and the situation that may not be there. Anger is also of course not conducive to creating an apology and influences people to fight in whatever way. If a person can't continue an argument they may decide that they should leave it be, that is to discontinue it and ignore the situation.
Leaving no room for an apology.
I wish I could say that I grew up in a family that instilled a sense of value on understanding what you did wrong and working to change it. This honest critique could have been followed up with a "thank you."
Instead failure was punished and as an insulator I started habitually apologizing for every tiny mistake from a young age, and not just my own.
Thanking somebody for help is a powerful thing. It helps you understand areas where you can improve. And when it is used property it can do a lot for you.
Instead of sorry, say a word of thanks.
I do find it hard not to apologies for a lot of the dumb things I end up doing. I find myself saying sorry so much, that its almost a default reaction!
This can get tricky though when things are out of your control.
I understand some people cannot help it. I got trained from an early age to arrive 15 mins early and the habit is so ingrained that my "running late" is arriving just on time (and scares the crap out of me every time I do it).
But people arriving late stresses me the hell out. One habit I fell into pre-diagnosis to cope was being a total, utter miser with my time, and someone showing up five minutes late would just ruin my entire day because I'd be obsessing about how they made me "waste" those entire three minutes I could have spent trying to force myself to get over whatever the ADHD challenge of the day was. I'm better than I was but it's still something I find very upsetting.
An apology communicates sincere regret and empathy, even if it's an apology made every single time because of things beyond your control. "Thanks for waiting" doesn't have that empathy, it comes across to me more like "I knew you were waiting and took my time anyway, thanks!" and that just sounds... presumptous. I didn't wait because I wanted to, I waited because I had to, what's the point in thanking me for it?
I'm probably being way neurotic here, but that's my two cents.
My friend wrote "thank you for your gift of cash" in her thank you card to me, and that's fine to use whether it's cash or check. If it's a gift card, say "thank you for the gift card."
I think she wrote another sentence but I don't remember it. My point being, you don't need to be specific. People get caught up on whether it's money, gift card, or a physical present, you can be generic and say "we appreciate your contribution to our life together," or something along those lines.
Close with "it meant so much that you were able to spend our special day with us" or "I'm so sorry you weren't able to spend our special day with us" (for the that gift but don't attend).
And then either "love" or "sincerely," names.
When I wrote thank you notes for cash/gift cards, I said something like
"Thank you so much for your generous gift! We bought a house recently and this will be very helpful to us as we get settled in. I've also had my eye on a for a while, and maybe this is our chance to finally get it! It was so nice to see you at the wedding..." etc.
I don't think people expect you to run out and plan/spend the money immediately, so it should be fine for you to stay general in the thank you note about what it will be spent on. In my opinion it might be safer not to mention the loan payments just in case anyone gets offended (it wouldn't bother me but some more "traditional" people might feel like it should go towards stocking your household with physical things). However, I would definitely still use the money to pay off your loans if that's what you and your husband agree is best. At heart, the gifts are meant to help you get off to a good start with your new family, so don't feel guilty about doing your best to make that happen!