My question is why is it impossible to get a large order right when I use the drive thru. There are days I have to pick up my co worker's lunches and because of time use the drive thru. I get back to work and items are missing or wrong.

The Drive through is not meant for large orders. So maybe that's why

I've never experienced this problem, but maybe give the McDonald's app a try. You or your coworkers can preorder and when you get there you check in and they bring it to your car.

Wendy's is no better

Using the app + going inside seem like the answer, plus you won't be causing a traffic jam for all the people sitting behind you in line, which can be a bit crazy at that location.

I guess you should try Wendy's