Many Thai's are stupid, you only need to ride a pedal bike or motorbike on any Thai road and the reason for the dreadful road statistics is very obvious.
The nice honest Thai person who runs after you to give you the 100Bt note that you left on the counter could very easily be the same person who then jumps on to their motorbike. comes out of a side road and on to a main road without looking then rides up the wrong side of the road. Yes, the average Thai person is decent and honest, but that all changes when they jump on to a motorbike or in to a car.
So Yes, the average Thai person is stupid. Sorry to be so blunt.