Big bikes used to be the vehicle of choice for ex-pats mainly and often on the routes South from Hua Hin to oil related destinations, where they worked or transited offshore to the Gulf of Thailand.
After being out of Thailand for majority of the Covid period, I see on returning that a lot of locals have big bikes now and indeed some very shapely young leather clad ladies amongst them!
I suspect that road users in general are not used to the speed and lower visibility of these bikes, in common with many other countries.
My wife’s male cousin owned a big bike several years ago, in the Ubon Ratchathani area. Unfortunately he too fell victim in a road accident, leaving a young wife and two young kids without a husband and father.