Even if your car is from the same brand as the dealership, they may not be equipped to service it. At what point does that become reasonable? Just how old is too old?
For example, Mazda rotaries are infamous for being unservicable at Mazda dealerships, even when the RX-8 was barely a decade old.
The point at which they’re no longer confident they can do a good job. For classic cars an experienced independent is better IMO because they’re willing to find non-OEM solutions that a dealership wouldn’t.
If you’re implying that dealers should be mandated to keep techs on staff who can work on some of their niche products then there’s an argument that if the manufacturer makes an unusual car they should offer support for it. But it’s not economical for most dealers to keep specialized staff like that, so you’ll be paying much higher than the already high service rates.
from working at the only mclaren f1 service center in na as a car washer for I learned that only bmw dealers are allowed to touch the engine so one of the local bmw dealers is wualified to work on it
My experience is that you really don’t want to take your older car to a dealer. My last experience taking my 2000 Porsche to the expert” Porsche dealer was a disaster and I ended up fixing it myself. I only took it to them because insurance was paying and insurance won’t pay you to fix your own car.