In the UK we have an excellent 0-to-5 point rating scheme for all establishments that serve or prepare food. It includes Street food vendors, kiosks, even schools. All sellers are required to show their "number" at the front door or POS, you can verify it online. You used to be able to see the inspectors report too (sadly it seems they removed that feature and replaced with a summary).
It's an excellent system that warrants repetition in other industries.
Regulation done right greatly improves one's position soliciting services - I want to know if my driver has had recent accidents, speeding tickets, has poor health, doesn't pass a DBS check, can speak my language (very useful in cities you don't know), that their vehicle is safe.