In every store I’ve been in, I’m the guy who has to take everything out of my cart and put it on the little conveyor belt thing. Self checkout is a second or two on top of that (which is usually made up by not having to wait in line) with no real additional effort (I’m already picking up and placing my stuff in a specific spot) I also can type in my number for the coupons at the same time I’m scanning my card, and move the bags into my cart as my payment is being processed, which ends up saving even more time.
The only place I appreciate a cashier is when I get a boatload of groceries at Costco, those folks are box-packing wizards.
Have you been in the American minimum wage job market in the last 10 years or so? Every job that pays minimum wage doesn’t give enough hours for the employee to be full-time, which means they don’t get benefits, retirement contributions, etc. In these cases, outside of the onboarding costs, a $15 an hour employee does in fact cost $15 an hour.