Car manufacturers also have their own service centers, yet we have laws forcing car manufacturers to sell parts to independent shops and customers. And over time market has established what a reasonable definition of "part" is, so they can't sell you entire engine as a "part".
they also don't sell you the lever switch that detect that the stick is in "R" position so WHEN it fails you either remove the "controls" from the trasmission block, open it, try to find the partnumber, hope it's correct and replace for about 100€ (10€ part + labour) or replace the whole "controls" part for about 1500€ (Stories from the workshop)
Better than having to replace the whole transmission block, but still not ideal
Or, this: we owned a 2011 Volkswagen Jetta Sportwagen TDI. It has a design flaw in its air conditioning system. It has some kind of automatic damper/valve that controls how the output of the A/C unit is diverted, and this valve gets stuck. The compressor is running yet there is no cool air coming out of the vents. After a while it might or might not start working properly.
The dealer's solution was to simply swap out the compressor assembly, which included this valve. Out of warranty this is an US$1,100 job, which is fucking ridiculous, and oh by the way I live in the Sonoran desert where summer temperatures get to 115ºF/46ºC, so we kinda need the A/C.
The independent shop across the street from the dealer said this was a known problem and VW should have recalled the cars and fixed. The indie shop also offered to replace just the valve for $500 including labor (the part was about $300 and the work was ... oy). The guy said they had to order the parts in from Germany because the US-based dealers and parts depots didn't stock it because why not screw the customers.
The kicker was that eventually the replacement valve failed too, and also the radio died (aren't car radios a solved problem), and boy was I happy when VW bought the car back because of their idiotic emissions cheating. Basically I rented the car for six years for $6,000 and the Honda that replaced it is still going strong.