Australia

Why the hell would you do that? Who's going to risk dealing with police and spending a day in court over some $5 item?

Even if you play the "whoops must have forgotten that" card and they believe you, you'll be put onto the "Check this shopper every time" list and negate the entire advantage of the scheme.

It’s a shame as it seems like an easy way to slip a few extra things in your shopping

Every so often (at first it seemed very frequent, then it dropped to much less frequently) it would pull you up for checking. It was pretty awkward, because you'd have to stand at the Scan&Go exit trying to get the attention of someone in the regular self-checkout or walking past in the store. Then once you got someone over, they'd pick 5 items from your bags at random and scan them, which would check that those items had been paid for. They were clearly trained not to just pick the items from the top, too, as sometimes they go reaching down to the bottom of the bag or go for other bags that weren't as obviously presented.

It's arguably actually harder to reliably get away with stealing than conventional self-checkout. Because in the latter nobody's ever going to check unless you cause an error to occur.