They do and the cities around the valley here often provide free trees to homeowners and have programs where they are trying to fill in as much as they can with shade. Some subsidized by the power companies I believe, to reduce power consumption by putting shade next to homes. I ride my bike a lot around the city here and there are a lot of sections with fantastic tree cover on paths and parks. Of course there are also barren sections, but trees can grow well and it is discussed often locally to plant them.