you don’t need a lot of computers there, it all can even work without communication with power company. on medium voltage (15kV) lines, that would be reclosers every few kilometers, and these do trip when short to ground (>0.5A) is detected. but no one does that on low voltage, because potential for damage is much less. the difference between euro and american grids is that americans have medium voltage line going down every single street, and because of low voltages and high power draw conductors would have to be of monstrous size otherwise. i understand that GFCIs are rather uncommon out there, and these aren’t usually installed in substations either. there are also lots of smaller transformers in american grid and that would make costs of putting all that protection circuitry even higher (in my home village there was 1 15/0.4kV substation per some 250 people, or 80ish houses. americans can have one transformer per one house) gas line could be plastic, so it would be isolating and so it’d be limited to that one house