Yea it's quite a contradiction but then again, most of the landlords aren't exactly up to snuff when it comes to standard business practices we're accustomed to in the west. There definitely seems to be a good faith element involved especially when dealing with Thai to Thai relations. It would seem that the landlords, in most cases, see if that if the bar stays open the chances for back rent recovery are higher than if they were to kick them out and hope to find a new tenant to take their place. Especially if it's a smaller bar not on Bangla, that slot could lay empty for weeks, months or who knows how long. So they'd rather let the bar stay open and see if they recover, at some point though they will pull the plug and this is usually only after they have found someone who is willing to take the old tennants slot.
This seems to be pretty common practice in other relations as well. A good friend of mine who's a motorbike taxi driver who also sells lotto tickets let someone buy $50k baht worth of tickets and promised to pay him back after they won, well they didn't win and now he's responsible for those tickets himself with no real way of getting his money back which is a huge hit to him as he doesn't have that kind of money. I don't understand this logic at all, as from my point of view I would have to be outright retarded to do this for anyone I didn't know personally but it seems this "good faith" attitude is quite common.