You can start a rule-breaking startup today in whatever stringently-regulated regime and worry about fines later when you hit it big (and the fines are often peanuts if you hit it big, imagine any late stage VC-backed company being slapped with a record $5.7m fine). Also, the age verification honor system is really pretty much a joke, it adds a little bit of annoyance and pretty much zero deterrence. Basically it’s about knowing to put up that page in the sign-up flow. So this “advantage” you’re talking about is fairly weak.