A few attempts were successful early on (passing items back and forth, one person moving something to the wrong shelf and another person picking it up, people dressing in identical outfits, etc), but the success rate in fooling the system was very very low. No method of trying to trick it that I ever heard of worked consistently, and it definitely seemed to get harder to fool the longer the store was open.
At the time I thought that whatever algos were being run on the camera feeds were getting better. Knowing that it was basically all manual, I'm not sure what the explanation is for the store seemingly getting harder to fool over time. Possibly just placebo, or people lost interest in trying so hard to fool it.
IANAL but I'm confident the legal answer is "yes", the same as if someone was using sleight-of-hand with objects at a cashier-and-conveyor-belt checkout station.
Whether charges are brought and how easily the case can be proved is another matter, but the intent is what makes it a crime.
To get a little pedantic, assuming such a promise existed, it actually doesn't mean as much as most people think.
A merchant saying "we won't sue you in civil court for the missing money" does not prevent the local government from criminally prosecuting that same person for theft.
American TV dramas often show the police asking people "Do you want to press charges?", but the idea that the question matters is a myth, since victims of crime don't get to decide that. At best, it's a terribly misleading shortening of: "Just for my own private curiosity, do you plan to lobby or press upon your local government officials into pressing charges?"
Exactly. Retailers generally assume liability for honest mistakes made by their system/employees and sometimes even their customers. However, when people knowingly exploit a loophole for financial gain it becomes fraud. Here's a real example - https://www.wfmynews2.com/article/news/local/greensboro-woma...