- We have this protocol to switch the streetlights remotely by modulating a signal on the main - but that's needing expensive hardware and it's cumbersome. Can't we just sent that over radio instead?

- There is all this decentralized renewable energy generation, we need a way to switch that off remotely if there is an overload in the grid - hey, we already have that hardware for swtiching streetlamps, let's just use that!

Of course encrption was never a concern and now anyone could remotely turn off / on power generation. But for that to cause real trouble, you'd need coordinated action that would require something like a state level actor.