Perfectly true. In the end, it is up to you to dig deep or not so deep into your wallet.

I am just wondering how an US waitress would look if I told her that 10% was a great tip in Europe, and that I would not care about the local customs...

Maybe it's just that I have a hard time to get all these threads on "how to blend in" and endless shoe discussions in congruence with adhering so much to what you are used to in the U.S.

Last year, I was not happy at a certain hotel which received high ranking in TA. I had to find another one for the rest of the stay. The only one I found cost a lot more but the manager decided to give me more that half price, actually it ended up even cheaper that the one I moved from, because there was an empty room for the 2 nights I need. When I got back to the states, I sent him a very nice silk tie from Thailand. I did not get any response from him. My British friend told me that it is normal. People like that do not expect anything in return. At least the hotel had income of 2 nights instead of being empty.