This is the real answer to the OP's question. Dealers track what their customers buy, and should pay attention to what prospective customers ask for. I'll compare it to the group pizza order. If you invite 30 people over to your house, you'll order a bunch of 1-topping pizzas, some fancy ones, and a few vegetarians/supreme because people say that they want it. However, at the end of the day all of the pepperoni pizza will be wiped out and you'll have a bunch of the specialty/veggie pizzas left. People say that want something but in the end its all about what sells. These dealers probably know that 70%/80%/90% (??) of their customers want the standard tailgate and so that's what they primarily have on the lot.