I have flown on THAI and EVA to Thailand, both are (or at least were when I last flew with them) pretty decent airlines.
The only real problem I ever had with THAI was that the first time I booked with them they quit flying to/from Amsterdam between me booking that direct flight and actually flying it. A quick hop to and a (too long) transfer at FRA solved that problem (without extra cost to me).
That is at least a pretty reasonable explanation, let's hope it is true.
My first thought was that they just don't like to do streetworks in the rainy season.
But that vendor wasn't using them. You could even have bought one right next to that cop without any problems, those would have only come if/when you started to use it in that location. Buying one to use the next day at the beach was and is perfectly fine.
She lost a lot more future custom as a lot more people read this and remember. I would nearly recommend somebody drop her a link to this thread and more specifically your post (and the reactions to it).
Never had the pleasure, but I bit further down (or up given the incline) that soi there also used to be "Nice With Ice", providing a similar service. It didn't last long (next time I visited Pattaya it was gone).