Tracking users via the electrical grid?

I just saw a comment where someone mentioned that the ~~gouvernement~~ government can track us using the electrical grid. I am surprised to know that something at this granular level is possible, I never expected that they would be able to identify individual devices when they are plugged in. Although maybe it shouldn't surprise me, I hardly have any electrical knowledge, and if devices can emit EMF to identify themselves maybe they can do the same over wired electrical signals …

devices electrical grid gouvernement government grid identify knowledge plugged in privacy surprise tracking