For a photo shoot of an engine lineup in a new car brochure, I spent 14 hours* doing the detail work on a V-8 that was a "pre-production 200k mile test engine" when it came in. Yes a true driver was used for a full page glossy image of their new motor. Yes parts get removed, some get painted, or polished others are replaced with new. Some get masked and painted in place, while some get their paint removed. Lots of prepping, meticulous masking, and hard work goes into it. Brushes, dentist tools, sockets coated in tape as to not scratch painted bolts, etc, and whatever it takes to get the end results are used.
In the case of a concourse vehicle sometimes parts need to be bead blasted, and other times custom parts are fabricated for their replacement part is nonexistent. Detailing in this caliber is beyond compare and super hard to estimate the costs, especially when so many are just clueless as to what's involved, but the final results are worth it when someone at a show, or an art director says" WOW! "
*that 14 hrs did not include the initial steam clean or the engines removal.