[saltcured]

I think it's really a simple, cultural bias. Most wanting 3+ bedrooms and having the means are also programmed to be inclined to want detached houses with a yard.

Also, in California, "apartment" means short-term leasing and is usually full of young singles, couples, divorcees, and retirees. It is often a big building with many studio, 1, and 2 bedroom units. A similar multi-dwelling structure with individual unit ownership is referred to here as a condominium (condo). These often have slightly larger units since they are targeting the home-buying family rather than the itinerant renter.

In SF Bay Area suburbs like Walnut Creek, there are also neighborhoods with town-homes. These are like condos in ownership structure, but often only have 2-3 units per building, wrapped with a small private yard maintained by the owners. And these lots are in turn surrounded by larger common grounds, which are maintained jointly by the HOA for the whole neighborhood.