I'm from EU with limited but not null experience of USA bureaucracy and so my question: I understand that taxes vary from a State to another and the arrested pe

I'm from EU with limited but not null experience of USA bureaucracy and so my question: I understand that taxes vary from a State to another and the arrested person is not there volunteering (meaning working for free) but for business purposes (so a taxed activity) and I suppose he will not pay taxes in the right State due to that license issue, an arrest for that sound exaggerated but anyway, any country choose it's law. What I miss is how such license scheme may be a guarantee against scammers. USA constructions have a very bad quality reputation in UE, laying on par with China, mostly due to the choice to be cheap and quick instead of strong and durable, but a license give no guarantee about how a company really operate. Normally license are obtained after a small bureaucratic procedure who formally give and ensure proper training and often just ensure some friends of friends milking a bit of money in useless and crappy training curses, even if that's not the case in the USA even a well trained professional can choose on purpose to work well or not. So where is the protection?