I have used multiple self-checkout stations in the United States that weigh items. If you add two cans instead of one into your bag, the computer terminal will inquire about it.

And security: You only need a single person standing there to scary away 95% of shoplifters.

I watched a YouTube video from the channel "Not Just Bikes" about grocery shopping in Amsterdam, Netherlands showed a supermarket where you carry the "pricing gun/lazer" with you and "beep" each item as it enters your basket. I have no idea how they reduce shoplifting. Can anyone comment?