Not all issues are routine.

So we schedule service, and then we throw away all the food anyway because the problem cannot be addressed remotely.

Agreed. I was just addressing that it's not exceedingly rare to need to get a tech out on site to address something. Should the manager be on top of this, checking temps on all the cases every day? Absolutely, but I can see the argument for a more automated system of monitors/alarms that can get a tech dispatched before the manager has even noticed the problem.