Access
Access is usually the single biggest variable. A supply line failure in an open crawl space is a straightforward repair. The same failure under a slab means locating it electronically, cutting concrete, repairing, and restoring the floor. Same pipe, entirely different job.
In Tupelo, this splits roughly along neighborhood age: older areas west and south of downtown are largely crawl space, while later development on the south and north sides is slab.