How old is this house?
In 1971, the US National Electrical Code (NEC) required grounded receptacles in all locations of the home (effective January 1, 1974).
https://en.m.wikipedia.org/wiki/Cheater_plug#Use_in_residences
You can check with a $6 electrical receptical tester.
It could be that the electrical system was grounded to the waterlines that enter the house (those should definitely be copper).
Reminds me of Coffee Stain Studio’s trailer for the release of Goat MMO Simulator:
https://youtu.be/WAm5yxQA_HY