Moving vehicle as they have a timer

I went to this branch today, ordered food at the drive thru. When I got to the pay point I had to get out of my car to get my purse out of the boot as I do not keep it in front by me. The lady told me that I need to park my car, get the money and reverse back in the queue as they work on a timing system. She was rude when I told her it will only take a couple of seconds as I have my baby in the car. There was no other customers behind me. It took me literally 10 seconds to get my purse and there was no need to be rude. I do not see the point in a timing system even though my order was ready I still feel it is fair that I check my slip and food when I receive my order. I felt like I was rushed so that they can make their timing targets. No care for the customers!