The Cashier Story is one of my favorite examples. When I was a kid, you had to pass a math test to get a job as a cashier.
And you had to know this skill called "counting back". The point was to - in effect - reconcile tbe cost of goods bought PLUS your change back to the original amount you gave the cashier. Nowadays cashiers have no clue what this is for...but they've heard it done so they dumbly replicate it. But since they've never been trained they don't count back up...they just "count your change" by reading out whatever the cash register said should be given.