If what's needed is the ability to monitor them, then why are these things remote-controllable?!
Obviously read-only access to some sensor is not the same attack surface as having the ability to remotely shut-down the refrigeration.
That’s exactly right. There all all sorts of read-only architectures where the device can be monitored without every directly accessing it:
- The device’s control has a radio transmitter that emits its readings, but no receiver. Listen for those messages to monitor it but there’s not a physical path to reply to it.
- The device’s controller writes a database or message queue. Its code never reads from that source. Monitors listen to those messages.
And many, many similar methods with the same core concept: the item transmits its status but doesn’t have a method to receive replies. You just have to commit to using any one of those thousands of mechanisms.
The fridges are cheaper to make because they don't need a bunch of knobs and switches and temperature displays - just an app on employee phones.
Read-only access is mostly an illusion that itself can be hacked to gain control.
because you might not want to send a technician to every single one of them once a firmware update is needed
Same reason website's are remote controllable. There's someone who's job it is, is to make sure the fridge is up and running, 24/7 and for the same reason that website operators/SREs don't live at each POP/DC, that fridge operator wants to remotely be able to flip some relays off and on to fix the problem without having to drive onsite, if possible. Additional, a single person/fewer people can then also be responsible for multiple/more sites.