system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does it seem like banks (and most places with cashiers like grocery stores for that matter) are always understaffed?

I get that part of it is related to costs. And maybe someone has worked out that the loss of client base due to unsatisfied customers is less than the cost of hiring more people but it just seems crazy that you wouldn't want a reasonable level of service if you intend to run a business.
gpt
Because odds are that you go there when most other people go as well. You see it as busy and understaffed but had you gone maybe one hour earlier or later the place could be empty. 

If these businesses hired more people for busy times, which might only total an hour or two per day, their costs would rise. When the cost of a business rises they either eat the loss pass it on to the consumer or a bit of both. 

So less of a wait in rush hour would make it more expensive for you and they would have people doing nothing in the slower hours.