Except as a way to gather data on you and demonstrate that while YOU are not worthy of their trust, they are implicitly entitled to have you trust them. Like I said, there's a lot more scummy bs in the average car dealership than at my house. If there is going to be a one way trustworthiness presumption, they have it backwards.
Except when you have an established relationship with a dealer. They know who you are. You're in their "system." They're not going to hassle you with a credit check.