"the best crawlspace of all is filled with concrete and called a slab—or dug out and called a basement"

New Light in Crawlspaces | Building Science Corporation 

unless the unreinforced slab is built on uncontrolled (not an "engineered " soil, e.g. contains organic material), uncompacted, fill--and is cracked--and the cracks in the slab cause the ceramic tiles in your entryway, kitchen, bathrooms, laundry room, etc. to crack. 

as for crawlspaces, where are all the "tiny people with good workmanship? ... They all have gone on to fame and fortune in reality TV cable shows." 

face it, folks. the quality of new houses in the US from top (roof) to bottom (foundation) in the last 50 years has gotten worse while the quality of goods and services in other US industries has more than doubled.