I'd be willing to bet that almost all of the actual foundation problems around here come from building on crappy expansive soil that won't drain, or from poorly thought out drainage around the structure, or both. Unfortunately, the majority of the soil here in North Texas is expansive (clay.) It is possible to compact expansive soil and get 90% rates under the right conditions, but there are 365 days in a year, and during most of them the soil will either be too dry (cracking) or too wet (saturated.) That pad that tested good once is destined to fail and then a portion of the foundation fails too. If the soil pumps under any condition, it'll never be a stable pad for a structure. Most of the clay around here will pump in "pockets" randomly with repeated traffic over a given area. I've even seen it happen with completely dry ground under drought conditions.
There's a reason that commercial pads are lime stabilized or replaced in areas of expansive soil...the native soil is junk and the engineers that will be held responsible for structural failure know it. Most cities up here are finally getting semi-smart by requiring soil testing prior to building of residential homes. But even if they do, compaction testing on a pad after the grading is completed and any thought process regarding lot drainage is a rarity. Proof-rolling is still an accepted method of checking compaction which is simply put...ridiculous.
In the county, the poor customer is at the mercy of the builder. A typical pad in the county is built by pushing the onsite soil up from the area surrounding the homesite, or with just a few loads of imported select fill spread on the surface. Either way...compacting in "lifts" seems to be unheard of. The bottom of the foundation is still sitting in expansive soil, so it's designed to fail anyway.
If I'm called in to do final and drainage grading after the home is completed, I can guarantee that unless select fill that passed the test was imported during the pad building process, any fill I use to accomplish the task will be better than the soil the home was built on. That's pretty sad.
I could go on with all of the homes I see built at the lowest elevation of the property, or below the bar ditch invert elevation...but that's a whole 'nother thing,