Earlier quoted context omitted.
This is the "lame - no wireless, less space than a nomad" take. Are the prices not listed on the individual items? Purchasers make decisions on a product by product basis, not based on the total. How often are you at the checkout and say "Wait, HOW MUCH is my bill? never mind then, going to go put some things back." Sure, it happens, but it's a 0.0001% use case. edit: OK, fair play to everyone who responded and said…
I was a cashier in college for several years. Your scenario happens far more than 0.0001% of the case. It's fairly common amongst poor people. Then there are items that aren't acceptable for use by food stamps and must be paid for separately. Then there is WIK and trying return WIK items for cash refunds. You also have people who misread the labels. Then there are items that aren't in the right place and the label sa…
Put a can of soup in your basket. Oops! The alert I set up for items that aren't covered by Food Stamps just fired. Let me see what the issue is. Oh! I just got an alert because I went over my budget, let me review my items and figure it right away.
And even if you don't have a smartphone/app, the process of going to a kiosk to review your order will be much faster than at a register. Walk up to the kiosk and it instantly shows what's in your basket, with a total and flags for non-Food Stamp items. Now you can go swap things out or put things back and the whole interaction only took a second and was must less of a commitment than going through a checkout lane.