I think this is the result of changes in the car business over the last 20
years. I think the following factors (and others) are at play

1) State laws protect dealers from manufacturers' pressure in most states.
This particularly affects older brands that have franchise agreements
written many many years ago. At one time Ford investigated trying to
consolidate dealer service in central locations and was slapped down in most
states. Ford's attempt to reward "good" dealers resulted in them being sued
by the "bad" dealers on the grounds that identifying good dealers violated
the franchise agreements. Some states also restrict manufacturer's from
owning dealerships. So they can't pressure dealerships, they can't own
dealerships, and they can't even pull franchise agreements in most cases
because state laws prevent them from doing so.

2) There are not many truly local dealers left. The Ford dealer I have done
business with is part of a giant company. They own multiple dealerships for
multiple brands. If Ford tries to push them over service issues, they can
just threaten to push sales of competitor's cars.

3) Cars are actually a lot better today than years ago. This means the
volume of high profit (i.e., easy) service business is down. At the same
time, many of the problems are much harder to diagnosis, and Customer
expectations are much higher. My first Japanese car was a 1975 280Z. When I
bought it, I thought it was really good. Today, I would considered it a
lemon.

4) There is a major disconnect between the sales and service departments.
The Ford dealer I use has the sales and service departments separated by a
half a mile. They introduce you to some guy who they claim is the service
manager, but he sits in the sales building. I've never even seen him over at
the service department.

5)  Dealerships underpay technicians and over charge Customers. This was
particularly obvious at one of the local Toyota dealers. It seemed like they
would hire a technician, train them, and them have them quit, and set up an
independent shop.

6) Ford (and other manufacturers) try to control warranty costs by
underestimating the time required to perform a service procedure. While the
times might be possible for highly trained and experienced technicians, they
are often unrealistic for a technician performing the service for the first
time. Naturally, the best technicians try to avoid such repairs. And their
is a tendency for shops to be less than ethical in an attempt to compensate
for a perceived injustice.

Ed