Thais have different Values than Westerners.
Westerners, especially from USA, prioritize Personal Freedom, whereas Thais prioritize Community Spirit.
Instead of trying to criticize Thais, live by your proverb, "When in Rome, do as the Romans".
Thais are better at adopting to foreign countries' cultures. There is a Colonial, superior attitude from some here.
Wearing masks is hardly going to kill you.
What would the Yanks think if Thais migrated there and told you to stop allowing 18-year olds to buy bloody machine guns, for example!
What do the Brits think if the new immigrants start telling you to dump your cultural values and start wearing Burkhas?
If you can't fit in, don't criticize, most of you are only guests, remember.