Very much what @happybeing said is what would happen
If Mrs Jones doesn’t pay her bills then even the big companies would stop working.
Mrs Jones has to pay the Electricity & Water & Internet Utility Bills, Plus a number of other bills (Rego, Petrol, Food, Etc) So when SAFE is at that stage it will be recognised as another BIll to pay (likely automatically with some APP the same as people can bPay schedule other bills)
So really the worse is an additional utility bill that has to be paid and most likely an automatic bill.
BTW a microwave with that smarts would be running a vault and quite likely paying for itself. The work of IoT devices is very small compared what a typical household would be uploading each week (photos, mailings, documents, etc) So paying for the households SAFE bill would involve much more than just the IoT devices and become part of the bill paying.
In isolation yes it might become a burden to pay an extra bill just to run one IoT device, but in the context of a household and its bills and SAFE usage the IoT devices are just a blip in the overall SAFE “Bill”