I really think it is no different to a parking fine or something, if people are given warnings it opens up a whole load of administrative burden, administering warnings, keeping track of past warnings, verifying identity, opens them up to challenge from others who have been fined. A blanket approach is necessary for the system to work. Plus where is the line for full on business, that kid may have planned to work that stall all summer, could have. Even a quite lucrative unregulated racket