yes.
And this could be allowed if that is the agreement Apple would have with the Bakers. And the agreement had with the booksellers. While it may not seem fair. If that is the agreement it's the agreement. The price you pay for a book may not be the price I pay. My business agreements for product A isnt' what you pay for the same product. Call for Price rings a bell for me.
Again, if that is the Terms they came too, I would guess they sell just enough or more Trucks (in value) to more than make up the loss for car sales. Even if not, if that is the terms it is what it is. Nothing "wrong" about it. Maybe a bad business decision but those happen everyday.
Overall point is, they can make up those terms. As long as its not breaking a law, and is acceptable to both or many parties involved. Its fine. Even if it sounds crazy to us.
The problem with your defence of this is you are under the impression Apple is able to act as it sees fit when in fact they are supposed to act based on fair and reasonable terms under the DMA. Asking developers of trucks to pay for the cost of the engine while developers who build cars get the engine for free are not neutral terms. The DMA is attempting to create a more level playing field.