Very interesting post for ex pats!
You are quite right in some respects, but one of the first things I noticed in Thailand is that many restaurants and bars don't mind you taking in your own food - in fact, only a matter of days ago a couple came into my local bar/restaurant with some street food, and the manageress strode over and said "Would you like some plates for that? (And no, she wasn't being sarcastic!) Since then, the same couple have returned a few times - not always with food, but they obviously appreciate the "ambience" of the place, and the manageress has attracted a couple of new "regular" customers!
One thing's for sure - it wouldn't happen in the UK!!!