> I lived for many years in China and Thailand, and toilets are free, clean, and plentiful there

I don't know about China but this was the opposite of my experience in Thailand. The majority of public toilets I encountered had an attendant you had to pay for access. Shopping malls / hotels / other places were you were already paying to be there were the exception of course.

I am ok with paying for public toilets if they are being kept clean.

In Japan, I've seen attendants looking for some payment to use bathrooms in hotels.