At Lowes, the policy is, ask a customer to view their cart or bag and if they ignore you and keep walking then oh well. The Loss prevention officer then will get with the local PD and get pictures of the guy.
Problem is somebody can walk out with hundreds or thousands of dollars worth of stuff and no one will do anything about it or they will be fired.
I shop at a Fred Meyer store, and there have been times when the “theft” beeper goes off on me almost every time I go there. It’s embarrassing, but very rarely does an employee actually come over and check your bags. I’ve tried without success to figure out what it is that triggers the beeper. I noticed during the Christmas season, it was a real “beep-fest,” with the beeper going off for about half of the customers. My theory is that a lot of extra merchandise is electronically tagged at that time, and busy clerks forget to deactivate them.