in-n-out employees are the best hands down. And they have to deal with ridiculous orders too, animal style, grilled onions, regular onions, grilled whole onions, fries well done, grilled cheese, 3x3s. However, I don't think it has anything to do with race. Look at the people each place hires.
in-n-out hires high school aged kids who, while young, appear to have their shit together and will do something with their lives. mcDonalds tends to hire people who will never have a better job than mcdonalds.
fhm, I believe In-N-Out pays better. They get a better quality kid working there. Someone who wants to get the order right.