2. On order accuracy, I think most people would do better if they just freaking ordered burgers all the way or plain. Everyone wants to subtract this or that and add the other. The assembly line, minimum wage workers have trouble keeping up? Go figure. They take too long? Wonder why? It gets much worse when they start having 57 different value meals with 389 different topping combinations each. This is fast food. Stop expecting it to be a 4 star restaurant.
IMO, joints like McDonalds, BK, etc. shouldn't even do the special order burgers. The whole point of going to them, vs a better place, is getting in and getting out. Don't want something on your burger? Take it off yourself. A guy I knew used to always do a special order with the rationale that it would get him a "fresh" burger vs one that was sitting under the heat lamp.
Part of the problem with McD level places is, I think, training, incentivizing, and the actual assembly line. At McDs, you have one person both taking orders and taking money. I can sometimes see why I get a regular coke instead of diet when I'm paying and the cashier is both counting my money and taking an order at the same time (especially a custom order).
Places like In N Out, Five Guys, etc. can do efficient and fast "custom orders" because of how they make their burgers, as well as the infrastructure of the assembly line. At In N Out, you have one person taking carside orders and another at the cashier booth. Both of them verbally confirm your order (as does the person at the pickup window, before they hand you your food).
They also seem to be able to incentivize their employees. It always impresses me that when at the cashier booth at In N Out, if the line is such that the cashier doesn't have cashier duties, I see them jump up and do other work until the line moves forward. These are almost always High School kids, and I find their motivation impressive. At McDonalds, the cashier just sits and waits until the next person pulls up.