The teaching profession in Thailand doesn't seem to have a great image?
That's probably a true statement. Have things got better in recent years? I'm not sure. Schools have to start paying more for starters. The salaries for teachers in Thailand have generally always been far too low and it's becoming an increasingly expensive country to live in.
I'm not going to go into the economics of it all but if we are to have schools that are staffed by professionals - they have to pay more! Schools aren't entirely to blame though. There are huge numbers of teachers out there who are just not up to it and do it simply for their money. Yes, we all need money to pay the rent but you have to have a modicum of affinity with your job.