The problem I have with that definition is that only in the case of a one-man shop would a "painter" do all that work. It's like saying the same guy who pours the foundation is also doing the finish carpentry.
In a real production shop, a painter doesn't do anything but mix paint and spray. He might be expected to color sand and buff. Other, lesser-paid people are the ones spreading/sanding filler, fitting panels, etc.
If you can drop a car off at a shop that's ready-for-paint, you should not be looking at a $10,000 expense. Conversely, if you drop off a rusty beater, expect to pay far more.
I guess it depends on what one means by "paint my car". I assumed it was for a complete body and paint work effort.
I would not have one of my cars "painted" by an assembly line of different people who do different tasks towards completion of a complete body and paint project. They guy I use does it all, from cutting out the rust, welding, body work and painting. That way I know that the perfectionism he embodies is present in every step and not variable among different people doing various tasks. Like I said, I was assuming show quality results. I generally do not restore rusty cars because I would never feel good about them if they were a patchwork quilt of welded panels. The cars I pursue generally have very little to no rust to begin with, which is why my range of cost is not too broad.