i am a PPG certified painter with 30+ years of experience.
i am just giving my OPINION on the subject.

i USED TO "pre-paint" cars in the past.
i did this because the lower solids, cheaper, materials would soak down.
by soak down i mean they look glossy after the paint job, but after a few months or years exposed to the elements the paint would loose it's gloss.
if you painted it, gave it a good bake job in the booth, then repainted it again. the gloss would really hold up.
the problem with doing it that way is if you use cheaper under coats the top coat looses it's durability. like building a really nice house on a sand base. no matter how nice the part you see is, it's only as good as the foundation it sits on.

now after using the very high solids modern products for over a year now i don't see the need to do it that way anymore.
i just repaired the first car i painted with the newer products a week ago. the owner really didn't take care of the car just drove it. he visits a commercial car wash every other week. never waxed it. just drove it like most people do.
i honestly have to say the area where i repaired looked as good as the day it left the shop last year.
i don't know the cost of them, i haven't tried to buy any yet. but the really high solids under coats, water based colors and special clears made for the water based colors are really nice. they are extremely fast compared to the old stuff. and they are much more durable.
the down side to the newer products are needing the proper equipment and properly equipped shops to use them in. if you mess up the water base colors they are significantly harder to repair than the solvent colors.

just giving my OPINION on the subject.