I think we can't underestimate that one of the biggest problems with all this is the poor quality of the software.

This is particularly shameful in devices that are so simple. Basically finite-state machines, something that everyone in CS should learn in 101 classes.

Is that easy to do?

My oven is hardwired into the mains supply. To power cycle it, I would need to turn off the circuit at the breaker panel. I don't think this is at all unusual.