Life is not too short to ponder this. The solution is simple and it boils me that big fast food corps cannot think for themselves.
1.) Todays ERP systems can predict and prioritize items to make ahead of time for that specific store location. Like in the 1990's at McDonalds for example they over made way to much stuff and threw out quite a bit when the items timed out on the hot plates. We now have very accurate systems that track trends so that they can pre-make most items and throw away very little. The food is not that good if it had to be thrown out. Conversly I remember the quality being better anyways on the hotplates.
2.) do not install a curb, or median so that should someone decide to change their mind, they can get out of line and leave or go inside. I would have politely left and gone somewhere else.
3.) Dont use the descretion of the shift workers, program the order system to recognizethat when a certain number of items are ordered, then mandate the person to either pull around to the waiting area, or allow the person to cancel the order and go inside. Follow this up with a big sign that say "limit XX items per order".