I use the dash carts at the Amazon Fresh near me and they are pretty slick and problem-free. The overall Amazon Fresh experience with selection and stock has had some teething pains but they've been getting a lot better recently, probably learning from Whole Foods.

Sign in with the app then you scan the barcodes as you put items in the cart and I think it does some combo of weight and camera stuff to verify. You can also see/edit the list of everything it thinks is in the cart on the cart's display. If it does mess up (rare) you can fix it on the spot easily and without assistance.

Then you just go walk through the designated dash cart checkout lane, it blinks green and you're done and you walk out with the bags and the receipt is in your account history. Unless you need an ID check for something then an employee has to assist but they're generally pretty quick, but most of my trips don't require it.

Compared to "traditional" self checkout it's WAY better.