Hm, for what it’s worth countryside Netherlands (achterhoek, to be more exact) has (had?) farmers selling their potatoes, strawberries or other produce just by putting them all on a big table next to a road, and putting a sign saying how much they cost with a little plastic container to put your cash in.
Also no human supervision, whatsoever.

Though I haven’t seen them as much anymore, and quite some seem to have been replaced by vending machines or disappeared completely…