Usually, when someone thinks about going to McDonald’s, it has a clear idea on its mind:
Arrive to the restaurant and make a queue until its your turn and you ask for your order. Then, you have to wait all the time that they are preparing your order (if they dont have the product ready, you will have to wait a bit more). When the order is ready, the cashier will tell you the total amount, you will pay and then try to find a table with your food tray (that probably would be heavy with the food and drinks).
What about changing the process?
It is way better to arrive there, decide what you want, ask automatically to a machine and pay at the same moment with your creadit card. Then, with a number that the machine gives you, you can go easily to find a table and wait comfortably seeing in which position of the queue is your order waiting to be prepared. Later, when it is complete, your number will appear in green and you can go to pick it up without doing any queue.
This way the way McDonald’s change their whole structure and improve the customer’s experience, by reducing the queues and making it easier for customers to wait more comfortably while their product is being prepared, rather than standing in line. Also, they offer the possibility to check the approximate time that it will take to be ready. Moreover, it is not only possible to pay with the credit card, because the customer could pay with cash when it goes to pick the order up.
This is a simple, but effective, example of who could a business improve the customer experience by changing the queue system.