I'll start by saying this: here in MN, brake flushes are much more difficult than say... Texas. Try opening a bleeder on a 10 year old vehicle in the Midwest. Times 4. That "quick" service can easily become an expensive repair. Sure, you could avoid this by applying anti-seize from day one, but that's not happening.
Going back to generic maintenance, after working almost 20 years in the indy business I can say with confidence that it's really a 50/50 split. It doesn't really matter what kind of vehicle it is, who owns it, how much money they have, etc. At the end of the day, people treat their vehicles equal to the value they place in them. The customer with the $75k Range Rover that whines about a $600 brake job (which they can easily afford) is immediately replaced by the working man and his Corolla which runs half that cost. That customer won't think twice before approval.
The overall cost of maintenance isn't really the issue, it's one's appreciation for their vehicle.