If I remember right, the busier and better the SO guy's route is, the more tools he purchases and gets a better price from Snap on. Thus, he can afford to deal for cash. When I was a regular Snap On customer, my guy on Long Island was one of the busiest in the country. Turnover on his truck was unbelievable. He was always willing to deal.
I can't remember exactly when this was, sometime in the 90's, a bunch of Snap On guys tried suing Snap On because their routes were not as busy as others and they couldn't get the same pricing. They lost their case and lost their routes because it used to be (Don't know if it still is) you signed a contract saying you would not sue Snap On when becoming a dealer.
When I was young and starting out, I had a truck account which was an agreement between me and the SO guy. I also remember when I wanted to purchase my first big box that was like six grand, I had to apply for credit with Snap On. That was separate from my truck account so I had to pay on both every week to stay current.