I’ve only had to explain it at one or 2 places (not exclusivly BK). I think with all the low carb and such, it is getting more common.
When they opened the new BK about 2 miles from the house, the first time I ordered 8 patties, the cashier had to ask the manager who promptly showed her how to ring it up. Every since then … never had a cashier bat an eye. Well, unless they are trying to figure out what all the patties are for.
Went though with our 2 dachshunds in the car and ordered 10 patties. The cashier said "stocking up for the dogs? (with a big smile). My wife (who was driving) said one for each dog, the other 8 are his. She lost her smile … LOL