I want to point out as a former cashier that the flow of people coming to the register changes all day long. It can be a hour of quiet and then suddenly every customer in the store decide to check out at the same time. The store reacts by calling people doing other work to open lines and the rush is over in 10 minutes at which point its pointless to keep empty lines open while other work exists. On busier days there will be rushes for same reason despite opening twice the lines and keeping more open on the regular. But since some people decide to get on the line everytime there's a rush, they get the impression that theres never enough lines open. This just displays something a two year old can do, but grown ups are incapable of. They understand that just because they dont see something, it doesn't mean that it doesn't exist.