This absolutely does happen, but part of the issue is due to the design of the self checkouts. The good ones are a forked conveyor belt design so you send all y

This absolutely does happen, but part of the issue is due to the design of the self checkouts. The good ones are a forked conveyor belt design so you send all your items down, pay, walk down to the end and bag your groceries while the next person starts their checkout and has their groceries sent down the other side. No congestion unless the issue is related to scanning the items or payment.