My personal pet peeve with getting fast-food, besides the poor nutritional quality, is the near-constant order errors. McDonalds is by far the worst at this. I attribute it to poor/lack of training for employees working the register and taking the orders. Even seasoned personnel have issues working with the registers, are not aware of the special deals, or just simply make mistakes too often. When I can, I try to persuade friends/family to go somewhere else instead of McDonalds.*
Back in the 1990's I was driving to a Hamfest one early morning when I stopped at a Sheetz gas station for food and fuel. Lo, and behold they had this touch-screen ordering system that printed out my order. My order came up on a display in the food preparation station and the attendants there quickly read the screen and accurately prepared my food. After using it once, I was CONVINCED that it was the future of all walk-in fast-food, maybe even the drive-through. Now that McDonald's is finally implementing this after 20 or so years have passed, it could solve their ordering issues.
Now, McDonald's only needs to improve the quality of their food. Right now it's at the level of SPAM, which is just above Scrapple and just below Dinty Moore Beef Stew.
* Our local McDonald's is by far the worst McDonald's I have ever been to, which includes several international locations as well as many domestic ones. (I believe that gives me the right to claim it as the worst in the world.) It's dirty, slow, and highly inaccurate. Wrong sandwiches, no fries, no drink (I had to ask if they still sold drinks with their value meals.), no cheese, onions when asked to hold them, wrong sizes, etc. I once went 3 years between correct orders there, 2010-13. My family is addicted to them for taste and convenience despite my constant pleading to go somewhere, anywhere else. They went 2-3 times per week as they pick it up on the way back from school events/practices. 2*52*3=312 I complained about them on McDonald's own website and left my phone number. They called while we were out and left a message for us to call them back. The number they gave me was disconnected.