Some of the top notch pdr guys CAN get dents out even in curved/contoured panels, but it takes so long to get it all the way out, many don't take the time to remove them completely.
I watched our old pdr guy work on a roof dent for almost 2 hours non-stop (brand new mercedes, not even owned) in my friend's shop, he literally worked the dent out further than flush, then worked it back down so that none of the dent was visible. Of course, he probably charged about 500 bucks to do that dent, but on a brand new vehicle, and a mercedes, that's nothing to a dealer if they can't sell it with the dent!
Wish I had pics of the dent in my wife's van, same guy worked it for about 40 minutes and got rid of it completely. That was back in '08 and it hasn't returned yet. Of course, there are many other dings in the car now, but I don't wanna talk about them...