You have never thought about the McDonald's drive-thru as a piece of engineering.
You should. It might be the most optimized 200 feet in American commerce.
Here is the number that reframes everything. In the US, roughly two thirds of McDonald's sales come through the drive-thru. In some periods and markets it has run higher.
Two thirds. Not a convenience. Not an add on. The main business.
The dining room, with the seats and the tables and the ketchup dispenser, is the side project.
Now the part that makes it interesting. McDonald's has spent decades fighting over seconds in that lane. Not minutes. Seconds.
Because when you multiply a few seconds by 13,500 US restaurants and a few hundred cars a day each, seconds stop being seconds and start being buildings.
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The lane is not there to be convenient for you.
It is there because it is the cheapest way ever invented to sell a hamburger, and McDonald's figured that out before almost anyone else.
Let me show you the math.