Some U.S. cities and counties do this, it's called open space. Thing is that it restricts the future growth of the tax base. Cities want more tax base, even to

Some U.S. cities and counties do this, it's called open space. Thing is that it restricts the future growth of the tax base. Cities want more tax base, even to the degree they'll approve building permits when city doesn't have the funds for years or decades for things like flood management in those newly zoned areas. And then cities are also beholden to the existing voters who, by and large, are intractable in the U.S. when it comes to building high density housing, especially when it needs to go vertical.