You find them unrefrigerated on the shop floor, but the supermarket - if their JIT delivery is efficient - are probably having them on the shop floor for less than a day. Do they refrigerate in transport, in the back-of-house?

In the UK the whole supermarket might be temperature controlled (cooled) where the domestic environment isn't.

Seems like it's probably pretty complex to work out

There's probably a mean indoor temperature above which refrigeration makes sense, for example.