When I was looking at SF real estate I was surprised to discover nearly half the housing market was built on landfill. And surprisingly few of those buildings are built on bedrock.
Though at some point I think code enforcement returned, especially for large buildings.
The landlady would always talk about how the house held up great during the '89 earthquake. But that didn't impress me considering the epicenter was in Santa Cruz.
Where there's enough money to be made, you'll find shady business people and corrupt politicians willing to risk people's lives and livelihoods for a buck.
Plus, the federal government will keep giving people enough money to rebuild on flood plains, so it makes financial sense to keep building in places that keep getting washed away.
As a contractor with a foundation that settled it's nerve racking.
That said, very few foundations that settle need to be repaired. The average homeowner thinks the opposite though.
I stopped my settling by draining mine, and the neighbor's roof downspouts to the street.
Even without that fix, I doubt my house would have settled further.
It's true that most buildings/houses settle.