> Even in the densest places there are still tons of single family homes.
That is generally the case when the zoning code forbids the construction of anything else; otherwise, density would increase progressively, largely via conversion/addition, and you would never see neighborhoods of single-family homes abutting commercial/multifamily neighborhoods, with a sharp line dividing them, as frequently occurs in modern American development. Anytime you see such a dramatic transition, you are looking at an artificial boundary created by zoning, and that means the properties just over the line on the single-family side will be simultaneously overcosted (because they are close to an area of high demand) and undervalued (because they cannot be developed to meet the demand).
That is generally the case when the zoning code forbids the construction of anything else; otherwise, density would increase progressively, largely via conversion/addition, and you would never see neighborhoods of single-family homes abutting commercial/multifamily neighborhoods, with a sharp line dividing them, as frequently occurs in modern American development. Anytime you see such a dramatic transition, you are looking at an artificial boundary created by zoning, and that means the properties just over the line on the single-family side will be simultaneously overcosted (because they are close to an area of high demand) and undervalued (because they cannot be developed to meet the demand).