I would question any traffic violation from a Thai police man, they know very little about traffic laws or any other law as i have experienced
I was in the outside (overtaking lane) at 05.00 one morning, indicator on , about to make a u turn, and was flagged down by a police man who tried to fine me 500b for driving in the outside lane, i argued i was in the outside lane because of making a u turn, several minutes later he waved me to drive off... thick as 2 short planks