With the exception of DAI, stable coins can be frozen at moments notice which means funds can be easily seized when needed. That's probably why there is no need for more stricter regulations.
The issue I have with these so called stable coins is the lack of transparency on Company assets that's supposed to back their tokens. USDT, for example, has been caught misleading people when they said 1 USDT is backed up by 1 USD. The fact is that it's backed up by USD and other (liquid assets).