I found
this guide and was flabbergasted at the number of people you're supposed to tip, at least according to this guide.
Grace grew up with money, and all of this stuff is second nature to her, while having enough money to stay at nice hotels and go to nice restaurants in still relatively new to me, so I just defer to her judgement most of the time, which, come to think of it, makes this like most other aspects of our life

.
I do find it dubious, though, as it suggests teachers should get $25-100 at Christmas.

This is wrong, wrong, wrong. As a general rule, it is illegal for teachers to accept tips/gratuities, is potentially a firing offense, and it is definitely unethical. I've offended at least a couple of parents by refusing or returning Christmas gratuities, but I am not going to risk getting fired and risk the appearance of bribe taking even if it is innocent just to make someone who doesn't know the rules feel better.
Gilda