Rechargeable batteries weren’t really a thing in the 70’s. For consumer electrical devices, batteries were one use, and anything that plugged in needed to stay plugged in while in operation.
Big advances in battery chemistry made things like cordless phones feasible by the 80’s, and all sorts of rechargeable devices in the 90’s.
They had electricity in the 70s. They were missing standards, but they had electricity.
Just tell them our pet rocks are now cameras and instead of a regular wall plug we have a tiny plug for charging tiny things.
Also they had the ability to do this back then, too. It’s just that there weren’t as many devices that needed constant recharging.
Rechargeable batteries weren’t really a thing in the 70’s. For consumer electrical devices, batteries were one use, and anything that plugged in needed to stay plugged in while in operation.
Big advances in battery chemistry made things like cordless phones feasible by the 80’s, and all sorts of rechargeable devices in the 90’s.