You are paying for a rental car Upfront. They do want to make sure you are not a risk to loan a 60k car to. What if you steal it? What if you are a straw man? What if you are so over extended there is no way this car should even be given to you? Credit Reports show that. Not that you have 20k in the bank and can use it right away.
Telling a bank that you want a 1 Pay does not mean your lower score is rated higher.
Your assumptions about how 1pays work is very incorrect
at a 650 score you would get the money factor that 650 qualifies for minus the 1pay discount, also it is far from an instant approval. I have had customers with a good score but light history get rejected. 1pays are not easy or instant approvals