How does the drive thru person at food establishments know which cars had what food when there are multiple cars ordering? This boggles my mind. Do they keep order? Do they assign you a number? Are they telepathic? How do they do it? I'd imagine they would have to see your face or your car first in order to know who got what food. At drive thrus, you speak to a box, not a person. So...how do they know?
The first order goes to the first car that shows up. The second order goes to the second car. You can't cut the line at a drive thru so it's pretty easy to keep track of.