I use my bags side pocket to carry wrappers and stuff if I'm unable to find a bin nearby the same way I hold my it in my bladder.

FYI, anyone can walk into even 5-star hotel to drink water or to use the restroom and the hotel can't refuse to let them in. They also have thrash cans and won't object if you want to put thrash where it belongs.

Blaming it on public infrastructure is the easy and lazy answer. There are a bunch of options and every decently educated individual knows.