Axalta, which I believe is the brand that superseded/bought DuPont's automotive paint business, still has a "single-stage" acrylic enamel paint product. GM used acrylic lacquer paint as Ford and Chrysler used acrylic enamel paint, only. In general, many body shops liked to use acrylic lacquer as it was less picky about having to have a completely "clean" spray area, with any "trash" usually being able to be buffed-out after it dried. I always liked the acrylic enamel paint (the old DuPont Centauri in particular) for its hard shine. Even slicker and harder if "hardener" was added to the paint, back then. Great durability, too.
Using the old paint formulas can be very problematic, as there have been many changes in the paint pigments over the decades since that original OEM panit was sprayed. Which brings in the newer computerized color analysis items. To get to the orig color via the current pigment selections.
It could well be that the re-spray paint was a "close match" color from another car brand or model year? Or a "stock color" of a particular paint brand?
EACH paint brand usually has their various surface prep items, prep methods, primers/surfacers/sealers that are matched to the desired "top coats" of color. Can't forget the basic "thinning agents" for the various temperatures at which the spraying happens! Which relates to how "fast" the paint dries or if it sprayed "too dry".
MANY painters, over their years of experience, know what works best for THEM, though. Which "thinners" they can get (usually for less money) that work as well as the "suggested" ones from the various paint brands. Same with primers/sealers/surfacers.
I concur that BC/CC paint just does not look "right" on cars that it did not come on. Too shiny, to me. BUT that is also what every "modern" painter has shot for years, so they know how to do it well.
As for "quality", as the current BC/CC paint systems usually produce a paint shine and slickness that far exceeds what any of the prior "custom" paint used to yield, NO need to even get close to the "I'm going to show this car" conversation! My recommendation is to just ask for the current OEM-level of paint results (which should be what they are used to doing on the newer cars anyway). This will usually mean a heated and ventilated spray booth situation, with great "dust control". Surface prep has to be better, too, than it was in the single-stage times. AND, BC/CC is acrylic enamel, not lacquer.
When IMRON was introduced, one of their selling points was that you could spray it onto aluminum foil, let it dry, and then crinkle-up the foil. The paint stayed stuck, no breaks or cracks. BUT it required a haz-mat suit for the painter to wear, due to the isocyanines in the paint! So only fleets like UPS and similar used those paints for long-term durability, back then. In the current world, plus their limited color choices back then, probably no need for that paint in the consumer market any more, to me.
THEN came "HVLP" spray equipment. High Volume Low Pressure, so less over-spray resulted. Plus automated "Spray Gun Cleaning Stations". No more running thinner through the gun to clean it out, spraying into the open air to do that.
I'm NOT a painter, but have followed the various paint changes over about 45+ years at the dealership and our body shop customers' shops. The professionals all make it look easy!
Just some thoughts and observations,
CBODY67