Don´t bother about big letter posts. You are travelling with a child. You can can chose to go either the Thai line or Foreigner. They can handle it in both lines and are very used to such situations. And, yes, I have experience of trying both ways.
Just forget it! The meaning of the word education and Thailand does not compute. They have tried for decades with the drive safe campaigns. Just asking. How long do you think people will remember this if they do not post it in the news once a week for infinite time?
Also, the Thai population is not ready for legalization of pot. It will just add the the massive amount of problems they already have.
Ok, they are undecided as usual, going back and forth. Nothing new, though! However, I hail the proposal of recriminalization, as the Thai population is not ready for a thing like this.