We also have them in Germany and not just in the countryside, but also in big cities. This very common especially in the current weeks in summer when all the fruits are ripe. But it is not so formal as in the picture, it is mostly just a plastic bag, or a cartoon box on a table with the price on the cardboard. Child toys, furniture and honey is of course available the full year. In the alps milk and cheese is very common. I don't think we have a special name for this, it's just somebody selling something.

This concept also exists in some smaller hotels, there it's called "Kasse des Vertrauens".

I think people who would steal something from them fail to understand that everything in society is based on trust. Stealing erodes that, and I can't comprehend living in a society were this concept can't exist. It seams to me that this is the meaning of society and civilization.

Edit: And yes of course that is all with cash.