Yep - saw it in Raleigh, NC when I lived there. I suspect any place that doesn't allow customers to observe the work being done. I go to a small garage where the chairs are about five feet from my truck - with no wall, window or blockage of my view.
I trust the guys completely...following the mantra of "trust but verify."
Look out at your local Target/big ticket stores.
We were double charged on an item (if the clerk holds it in front of the scanner longer than a certain time, it will ring it up twice and the second charge is "coded" into the reciept- you will see a charge but it will read as a code but you can tell because the price will be identical as the original item scanned.
A few people were overcharged this way and we all went to the counter and complained. Their excuse was the scanner is sensitive, but we believe it's a scam. They double charge you for an item and then pocket the difference in cash, the store will never see the difference stolen because the cost of item is so small, and us customers are paying for it. most people probably won't notice the double charge.
Sorry for long post.