I don't think so, because people will figure out the weak spots and share this information. It will become a sport and people will think "last time I grabbed the milk like this, and they didn't charge me for it, what if I do it again tomorrow?" Hackers will start wearing special clothes with dazzle patterns or with grocery items to fool the system, etc.
What you're describing is no different than the thief mentality that exists today. Most people don't care to steal a carton of milk just because they can. And there's no denying the cost effectiveness of removing your checkout staff or else this tech wouldn't exist.
