Round here there's a lot of people who pay some bloke a fiver and he does something to the key that puts £50 credit onto the meter. No tampering with electricity and he doesn't even need to enter anybody's home, so if she's doing it that way the safety concerns wouldn't apply.
I've been on benefits a few times and it can be a struggle to make the electricity last, a lot of people have pre paid meters because they are on a low income or benefits and I think it's crap that the people with the least money are made to pay higher prices for electricity and gas, I won't lie and say I wasn't tempted to get £50 quids worth of leccy for a fiver but I'd be stressed about getting caught and knew it was wrong. It's tempting thin when you've got a tenner to last and leccy is low.
One of the bloke who fiddles with the keys reckons the majority of his customers are people who can easily pay for their normal usage, people on decent incomes and own their own homes and have good cars etc.
MIL did do it once or twice, she was on benefits but managed so didn't need to do it so to speak, and she got caught a few months after, she had to pay the company the full £100 pound back, which they did by taking it off her electricity meter, meaning she did end up struggling. I'm not sure how she was caught but I'm guessing when clients have £100s worth of leccy without the company getting a penny it won't take a genius to figure it out. The receipts from pay points have warning about buying leccy this way and say you will get caught.
I think it's wrong, but do understand why people on low incomes do it. It really isn't worth it though as when they caught it's not free, they have to pay it all back.
I wouldn't report someone though, even when money is tight, me reporting them won't make me any better off, I'd rather utility companies didn't charge those with the least money the highest prices, just like id rather instead some of the working poor argued for better wages rather than complain about the benefits given to those who don't work and push for governments to cut them.