You have been shopping. You walk up to the pay station. There’s a line. You put your bags down and fish into your pocket for cash to pay for your parking. You realise you might not have enough. You pick up your bags, find the closest ATM (which is usually on the other side of the mall), withdraw cash, get back, stand in line. You put in a note. It pops back out. You flip it, turn it, twist and eventually you pay. (If you had enough money, in coins, you probably had to scratch at least one coin against the pay station because it keeps sliding through and popping out.) Head to your car, drive...