This analogy is so bad, it is not even close to what is happening.
I will try and adapt to cars for you(I dont know why), but this is just really really bad.
Say you have designed a car, you can produce them on a very small scale, but you have come to valve(they make cars now) to mass produce. They do so, for a 30% cut(that reduces the more they sell) for everything they sell from their direct sales at the price you have set. There is no material costs or labour costs, just that cut of the price you have set.
Now valve have a sales page and are selling, and you decide that actually I would like more people to see the car, and so you consider selling it at other dealers. Valve says, sure, you can even have the cars for free from us(no 30% cut) and you can have basically an unlimited supply of free fully built cars to sell else where. We only ask that you sell the car at the same price you have set with us if you are selling a car we made.
You want to go sell it new cheaper? You are more than welcome too, but you cant sell the car we produced.
Such a bad analogy, but that is closer to what is actually happening.