I asked the management why they did this, because it was chronically understaffed, and required customers effectively check out twice if they were buying items from this section and the rest of the grocery store. Their response was that it was the only practical option to keep the store open, because otherwise, the amount of shoplifting taking place was going to render the location unprofitable.
So yes, this is a very real possibility.
This isn't directly related to shoplifting and theft since the high priced items are usually behind the counter, but if you are a grocery chain with hundreds of stores the poorly performing ones are always going to be closed first. And those are almost always in urban, crime-ridden areas.
[Source: worked as a supermarket cashier as a teenager.]