In 2008 I rode the day train BKK-Sisaket in Isaan. It was slow but fine, and part of the overall Thailand experience at that time for me. Jovial atmosphere onboard. There was food service and you could buy beer. You could stand outside between the cars and smoke a cigarette. The world was more relaxed even a scant 15 yrs ago. A lot of the fun has been sucked out of so many things these days. Perhaps Thailand could update and improve its train infrastructure, but it shouldn't be trying to sanitize the whole country. It's not Singapore, never will be, and travelers don't come to Thailand expecting it to be. Therein's the charm.