The question is about the dealer, right? The dealer isn't providing this financing to you, Alfa is, and they're paying the dealer that same "On the Road" price when you finance the purchase. So the dealer gets the same amount either way.
The financing, through Alfa, means your payments go to Alfa. And they're willing to give you 3,000 towards purchase of the car at the dealer in order to motivate those who can afford payments but not full cash for the car. They end up selling more cars this way, keeping the factories busy and employees and stockholders happy along the way. At least, that's how it's supposed to work out.