None of that has anything to do with quality over quantity. I don't care whether it costs or makes PD money to put the standards into a PS4 game, them doing so is taking quantity of cars over quality. It's a rather simple concept, if you include something of a lower quality purely to increase numbers, it's quantity over quality.
Here, have a box of 10 cakes. 5 are a bit dry, bit of mold perhaps on one, but 10 are better than 5, right!? I've already made the 5 dodgy ones so you might as well have them!
It baffles me your lack of understanding of simple concepts.
Let me clarify why your claim is not sound.
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Regarding the concept of sunk cost:
There is no trade off between quality or quantity for the inclusion of standard cars.
Let X be the total of premium cars.
Let Y be the total of standard cars.
In game A you have all premium cars, so you have X quantity of cars.
By joining standard cars, one or all of them you don't need to sacrifice any premium car. This happen because the standard cars are a sunk cost, they are already produced no matter if you use them or not, which means they don't have any effect on the amount or quality of premium cars.
The decision is not between: [All of X] or [X-n + All of Y], being n the number of cars sacrificed due to the inclusion of Y.
The decision is between: [All of X] or [All of X + All of Y], which can be translated to an "and": either X or X+Y.
This is enough to prove your claim as unsound.
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Regarding the concept of average
I will use your own example.
Box1: 5 good cakes.
Box2: 5 good cakes + 5 not so good cakes.
As long as the 5 not so good cakes don't harm you in some way (negative utility), and don't have any cost at the moment(sunk cost), then I can safely say Box 2 is the rational choice. Why would you throw away the 5 not so good cakes? Your 5 good cakes are always guaranteed, so they mustn't be an argument used for the disposal of the 5 not so good ones. This is true even if the average quality of box 2 is less then box 1. If the argument is about average quality then the game should only have one car: the best of the premiums, because each additional car makes the average quality a smaller
quality quantity(it has diminishing returns).
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What I am saying is not a matter of opinion. Your claim that is either quality or quantity, implying a trade off is not sound.