When I lived in Bangkok in my early 20's during the late 90's, we would be randomly stopped in taxis by Police all the time. Early 00's also.
Around 2016-17 there were Police checkpoints on Asok-Rama 3, so every time I went out for a drink along Sukhumvit and was heading home at the wee hours, my taxi would be pulled over, and I would be searched. This happened about half a dozen times before I moved to Chonburi.
You must have been extremely lucky.