Our local McDonalds employs most of their window staff with young people who speak Spanish as a first language; very minimal English. It usually takes at least three personas to calculate my correct change when I pass them more coins than es necessario. I’ve actually had them hand me a dollar bill while shorting their register because they couldn’t comprende the transaction.
I’ve run into that also. As part of a transaction once, I gave the girl a $10 and she tried to give me $20 back. The worst one, that still makes me laugh, was the young clerk who added a zero to the end of the bill when entering it. She started to try to give me over $180 back. I explained to her that this was generous, but I gave her one $20 bill and she was trying to give me 9 back. She was still lost. I swear, it took her, another clerk, and the manager to figure it out. Sadly, they cancelled the order, rang it up again, and reentered what I gave the cashier in order to get it correct.