The issue of many tourists renting a motorbike nd not having a license to drive such is a known issue and nothing is ever really done about it. However, time and time again we hear about people having an accident and their travel insurance or even their own HI policy not covering the medical bills because they did not have the proper license and therefore are looking for funds via a GoFundMe account. True, many many Thais ride unlicensed but then no one ever see's them getting stopped in the tourists areas, but out in the provinces and even when I lived in Nonthaburi they were being stopped at the checkpoints and being fined/cited and the bike parked. A neighbors daughter was injured in a motorbike accident out here in Pranburi, she is Thai, and the 30 baht scheme covered her medical treatment, yet I am unsure if she told the clinic she went to how she was injured.
Anyone renting a bike here should be properly licensed and wear a helmet, it is just common sense.