500k a month turnover is not a small store though. Also it'll likely be more for rural places where stores are smaller.

Local grocery store for me doesn't even crack 100k a month I'm pretty sure. I don't think they'll even get close to 10k a day on st. john's day, let alone any other day of the year.

Don't forget that cash also means more errors (which in sensible countries do NOT come out of the pocket of the clerk, but rather eats into the store's margins) and requires extra insurance because there's always that tiny risk of someone literally robbing the place. And sometimes the employees themselves will pocket some. You'll fire them, but it's not like you're getting any back.

You also need a safe, though luckily that's a capital expense rather than an operating expense.

You can more or less say that cash has a level of natural loss attached to it. I have no idea how it compares to the ~1.5% that you'll have to pay for card payments, but it's not zero.