I've been using an airbrush since 1970, probably painted 400 to 500 cars with them, first using cans of Propel until I could afford an airbrush. My first couple hundred freight cars that I painted are now in a box, because they're Athearn blue box, which is all there was at the time, and the Floquil colors were all I had, back in the days when there was only one boxcar red.
Today I'm between airbrushes, because my Wren finally gave up the ghost. I haven't needed one quite as much in the last few years because I've been building so many cars like Branchline where the lettering and the color are finally good enough. But I still need to paint trucks, underbody details, couplers, etc., so starting ten or fifteen years or more ago I used the Floquil rattle can for a lot of stuff that wasn't a special color.
I'm just about out of almost all the colors now, but I have been able to get the Scalecoat II paints (yes, I agree the nozzles are better than Floquil) and there are a better selection of freight car colors that I actually use.
Soon I'll need to buy a new airbrush, and I'll buy a new compressor to go with it, because I've got some stuff under construction that will need colors that don't come in a can. But I have had several years worth of backlog that didn't need airbrushing, so I've gone with the flow.
I can use some king of flat overspray if I don't like the gloss, but usually those detail parts just get oversprayed with the rest of the car, so no big deal.
And yes, I have painted entire resin cars with spray cans, but mostly black, and I can't tell the difference after a bit of weathering.