Because of the huge inflow of Russians it is now - apparently since about a months or so ago - very difficult (and much more difficult than before so all the comments that somebody did it a year ago are not really very relevant unfortunately)
There are, but you can also get a bona fide international driving licence from your home country which then is valid together with your foreign driving licence at least a certain amount of time after entering Thailand (which somebody on a tourist visa presumably does regularly)