The kind of meters we used to install 50 years ago would turn backwards if electricity flowed backwards.

So if you spent a week with the meter connected normally, then you swapped the input and output cables around for a week, the meter would be back at zero. Free electricity!

They used anti-tamper seals to make it more detectable, but there are ways around that sort of thing.

I assume the scam would be you rewire the breaker so the grid is on the apparent load side. It's not exactly hard to do, just dangerous.

Maybe it looks like you're trying to trick the meter into running backwards?