Everything, they, the US government has used elsewhere, high-tech crowd control, high-tech drone spying, etc. For example, like whats used on the US/Mexican border, is coming to every American city. I am thinking the South Pacific islands as a getaway; for, life in America is losing its appeal.
It is my understanding that smart meters allow the utility to identity which circuits within a a home are being used, thus identifying to some degree where people are inside the home as well.
This has actually been going on for decades, it's just now reached a fever pitch of violations of the Fourth Amendment, the highest law in the land.
We are already so far down the slippery slope of "1984" spying, I don't think there is any privacy at all anymore. All electrical devices can, for pennies, spy on you at manufacture. That is their motherboards can posses mics and bluetooth for virtually no cost at all, and the data can be leapfrogged from one device to another.
God I really hate this century...