Which we are, so that’s fine. It’s fine to have your opinion, but to assume it is so universal as to be part of the rules of grammar is a bridge too far.

Yes, living in the US, it’s safe to assume that any tap water is safe to drink without boiling. Sometimes it doesn’t taste great because of mineral content, but it’s safe with very few exceptions.

That’s also been the case in any developed country that I have visited, including Iceland, Canada, pretty much all of Europe, Japan, Korea, Taiwan, Singapore, etc. There may be exceptions in all of those places, but in any large city in a developed country you can drink the tap water.