Why Estonians invite strangers into their back gardens each summer

Swabia has something similar for wineries: Besenwirtschaft is a temporary small restaurant with very lax regulations. The main obligations are: at most 4 months open, at most 40 chairs, only cold food (often bread with lard), the wine does not have to be produced by the owner themselves, but the grapes have to be.

They are „advertised“ by hanging a broom outside (Besen is broom).

You tend to go visit a few over an afternoon, because they concentrate on certain wine-making towns.

Similar in neighbouring Latvia. Friends who recovered their grandparents' nationalised farm organised one there. They got to meet neighbours who lived there during the occupation. Pictures surfaced of the transformation into five tiny apartments in the late 1940s.

Can't imagine the food safety institutions even considering pop-up home cafes in my native Belgium.

Orthodox Jews do it every Sukkot :)