Weird, electrical grids didn’t exist before the internet?

They sent the data along the lines. Initially that was just the frquency. Drooped low? Ramp it up, running high, turn it down. That is effectively a spring mass damper system and it always had instability conditions that caused problems. They begand to modulate additional data, including voice, analog over the lines to add additional controls. As more people joined, and load became less predictable even that wasn't enough. Every endpoint now measures load at something like 30hz and that won't fit across the lines. They added separate dedicated fiber or microwave along towers. Those still get used. Probably sometimes unencrypted still. They are targets I'm sure. Then we have renewables and nuclear with their mostly inflexible power supply, that makes it harder to stabilize yet. The control loop stuff is often physically separate, but that is the older stuff and less secure. The data from all those houses still has to get onto the logically/physically isolated control network somehow, so that is a vulnerability too. Anyone with a zigbee radio cam see the encrypted packets.