Have you seen the markup on car spare parts? If you want to build a normal German family sedan from just the spare parts, you'll be paying 20x the cost of a full car easily.
Not even speaking of the skullduggery the VAG consortium is doing, they use the exact same parts for a large portion of their cars, just with different serial numbers.
A widget for Premium Car costs 1000, the EXACT SAME WIDGET for Budget Car costs 100. You just need to know the magic number or have a friendly salesperson behind the counter.
There are abuses. But for cars, even with the insane markups, having car parts is still a win, specially compared to tech devices like iphones.
Also, cars are 1) a bit more complex 2) a bit more granular in design, which leads to more swappable components. This result in needing to replace just a few relatively small components in case of breakdowns (a pump, a filter, etc), and even with the markup, repair is often a good solution financially vs replacing the car. By contrast, on a phone, the individually swappable components are much bigger (a whole screen, a logic board, etc), making repairs less viable.
Last point is supplying spare parts is also quite complex logistically, which explains part of the markup. But not all of it, I agree, there has been numerous cases of price fixing/abuses, for example: