Here is what Freebirds' quesadilla looks like: (apparently, at least. I've never been there)
It's a bit more loaded than the average quesadilla I've come across, which is usually no more than a few ingredients (cheese, meat, peppers/beans) with sides of salsa or sour cream. It looks like your cheeseless quesadilla could have been made, and it should have been made for you... after you were explained what was wrong with what you were asking for and you verbally agreed to have this monstrosity constructed for you.
The problem the restaurant has is that, if you actually are some idiot who doesn't understand what they're actually asking for, you'll either have a negative opinion of the place because the food sucks or, if you complain, they'll have to remake your order. Either result isn't desirable.
Looking at their menu, though, you should just order their burrito salad bowl things. It's everything you want, even down to being best suited for knife and fork eating.