At Costco you have to show your receipt when you leave and they check your items. Walmart used to occasionally ask but they stopped doing that a few years ago. Showing a receipt does not bother me if it helps deter thieves.
I was surprised when I was staying in the bay area a few months ago that the local Safeway had a guard. The clerk told me every week some guy comes in with a garbage bag and he grabs a bunch of meat and whatever else he can grab and runs. Even with the guard there, they are not allowed to chase or try to stop the person. Why are they paying for a guard?
My husband occasionally did events at Home Depot and he said it was a frequent occurrence that thieves would load up a cart, often with copper pipes or other expensive items, and run out through the exit. Again, the employees were not allowed to try to stop them or block them.
Recently I was at Trader Joes checking out when they had trouble verifying a hundred dollar bill. They took it and the person left with their groceries. I told the clerk about a time at a different Trader Joes when someone had tried to use a counterfeit bill. They give the fake money back to the person and said they couldn't take it and the person paid with something else. The new clerk told me that their policy now is to give the fake money back and let the person leave with their groceries unpaid! I asked the clerk if I could come in with monopoly money and play that same game!

Just kidding of course. That also really surprised me because I always thought counterfeit money was a serious federal crime. I would think they would at least take the bill, not give it back.