Electricity theft is an old thing, even with the new technology where most power meters are electronic and you can't slow down the spinning mechanism, people figured out ways to use EMPs to modify the meter or stop it altogether, so IMO, BTC mining hasn't changed anything in that regards, people just improved the result of their stealing.
Steal electricity is a very old crime and can to some extend be easily done. But to steal electricity in some remote location where you are not present yourself is a new level. You can basically steal electricity at one point of the world and mine bitcoin with it. Your location is however in an totally different country and with the mining profits you can then buy legally energy. It is basically like an infinite energy storage and transfer setup.
Same could also be used legally however. You have solar power during the day, that you use to mine bitcoin. During the night you buy electricity from the city with the mining profits.