That's because market-economy developers expropriate planning properties that lead to higher quality of life, externalizing the resultant downstream costs upon their customers, who in this instance of a market with highly asymmetrical information between parties (out of many in market economies) are not aware of the longer-term, cross-functional factors decided against their interests when they make their housing purchasing decisions. This is only somewhat mitigated by customers gradually over time (a few generations) building up a kind of institutional knowledge of preferences that painfully slowly express themselves into the market, and quickly vanish if not assiduously and consciously protected; see many much older walkable neighborhoods in less well off sections of towns and cities get gentrified over with less walkable developments.