It's not immediately obvious to me why fridges in supermarkets need remote control; a supermarket is a place where there are always people, it's not a base on Mars. And even if a remote is needed, it should probably not go further than the manager's office.
I don’t know to what degree control is needed, but remote supervision of cold holding temperatures is good to make sure food doesn’t spoil. Most places that don’t have networked fridges have staff manually logging the cold holding temperatures to make sure things are working.
Again, though, I don’t know about making changes though.
The other, more likely, answer is that there’s a diagnostic mode that allows raw control of the system and no one bothered to require physical presence to enable service mode.
With remote firmware update capability, at attacker could easily brick the entire fleet. With just service access it could be possible but would be more complex.
Having networked telemetry seems like a good idea, just not sure why they would need remote control too - that seems far more dangerous than necessary.