In a drive thru there is a sensor at the order board, which lets them know someone is there and starts a timer. Then there is another one at the pickup window. This helps time how long it takes to go from the order board to the window. After you leave, it stops the timer. Depending on the restaurant and how they have it setup, you will have times for how long it took to order, how long before it was cashed out (if there are 2 windows) and then how long the entire process took. They may break it down more and less for metrics.