In my area, the builders “usually” use CMU w/cap and then shimmed Piers, even if the perimeter foundation is poured. We are also required to vent Crawl Space area, required to install 6mil minimum Poly Vapor barrier and all cellulosic materials (wood,cardboard, etc) should never be stored in the crawl, even on the poly vapor barrier. Our Eastern Subterranean’s will eat right through vapor barrier, even through vinyl liner pools. Again, in my area, floor insulation is an option, typically not used unless the builder is building Green/Earthcraft construction.
All of the above (except for Piers) is mute if you go with a sealed vapor barrier crawl space system.
The Code/Inspection industry and the Dept. of Agriculture are having a hard time getting a grasp on this relatively new industry in the south. If you’re not familiar with this service go to www.crawlspace-basementsolutions.com