Your absolutely right , There's "the right paint" for each job,most jobs are just sanded and painted at body shops,very few will do a resto these days because nobody wants to pay for it.
I guess thats why theres such a big market for lower end paints...theres a big demand.... The thing is ,buying the best paint wont necessarily get you a nice job,you have to be a good painter, a good painter can make any paint look good.....So for the (first timers) a 500.00 paint budget will get you to the same place a 2,000.00 and up budget will..You wont see any difference.
but get the good cheap stuff ...some of the stuff out there is real crap..
Ask a "painter" whats the best paint for your budget not a dealer or anyone that sells paint ...find out what shops are using it and see how it looks for yourself,and never buy on price alone...
The bitterness of poor quality always lasts longer than the sweetness of a good price.