You don't speed up checkout because people care about faster checkout, you speed up checkout because people care about lower prices and faster checkout reduces fixed costs, or increases revenues allowing you to lower prices.

If checkout lines are supply constrained (eg. there are always lines) then increasing speed increases throughput which increases revenues.

If checkout lines aren't supply constrained (eg. there are empty checkout lines) then you can reduce the number of open lines without increasing wait times, reducing your headcount and driving down your labor costs. If you lower your labor costs you reduce your semi-variable costs and you can keep the same contribution margin and lower prices.

> Is checkout speed really limiting factor in grocery store growth though? Like are people that sensitive to the few extra minutes (at most) at the checkout counter they'll switch where they shop?

Have ever been inside a walmart? There's only ever like 2 checkouts open and massive lines, that's a long time to stand there.

Waiting in line at the grocery store I thought was one of the most common annoyances people have?

Sometimes I just leave the store if the line is too long. More often I just don't go, knowing it's going to be too long a wait this time of the day.

Perhaps I am an impatient outlier, but whatever the profitable wait threshold is, it could be maintained with fewer cashiers if checkout were faster.

I shop at 1am or later at 24 hr stores just avoid waiting. Life is finite. Not enough of it to waste in line.