> It is highly contestable that every single Western supermarket out there has a diesel generator down in the back / storage room that will kick in in an instant if a power outage begins.
Literally true. However:
- If it takes them 10 minutes to fire up the generator, then 5 minutes to restart the network and registers, that is no big issue (in a many-hour outage)
- At least in my part of the USA, many supermarkets do have generators - because storm damage causes local outages relatively often, and they'd lose a lot of money if they couldn't keep their freezers and refrigerators powered. Since the power requirements of the lighting and registers are just (compared to the cooling equipment) a rounding error, those are also on generators.