I agree that there are not too many mechanical differences between a non-SVT vehicle and a SVT vehicle be it a F-150 or a Mustang. SVT definitely has a marketing portion to it. I also am under the impression that SVT development is a set of engineers separate from the other development engineers at FORD which allows for deviation of parts from the normal production vehicle, while still being under the same production line constraints.
As for the mechanic the vehicles should be very similar. I was just thinking training on specific problems/differences would be a good thing for the mechanic. I do know, first hand, that some dealerships pay for training their techs regularly and others don't do so much. Your milage may vary depending on what is important to that particular dealerships leadership.
In regards to your main point, that the mechanic does not care because it is not their car, I personally think your 100% right. I don't think all tech's take this attitude because I would like to think that people still take pride in their work and good jobs. I think you find this pride more outside of a dealership with personal shop ownership, since it is really the tech's name on the sign.