Apologies for adding my 2p's worth.
Because the number of Audi dealers that understand the RS models is a tiny subset of Audi dealers...
There very few Audi dealers that understand Audi cars let alone ones specific to the RS4, in my experience of dealers in the south west, they're all <beep> with a few variations on the same theme. The bigger and flashier the dealership, the higher the labour rate and the more <beep> produced.
It would be more effective to highlight the positive experiences relating to RS/S ownership, if its not BS from the service admin 'that's not a fault it's a characteristic' it is unecessary repairs recommended by the technicians because they are on a bonus scheme or necessary repairs that are not completed properly.
Example booked a service Saturday morning, arrived 5 minutes early so had to sit on the door step until they opened as not allowed in, you get better service in McDonalds.