I've always noticed that in Florida, where I've lived most of my life, it's always cooler under the trees, much more so than in areas shaded by other things, buildings,etc. I don't know if it has to do with evapotranspiration, or by energy being absorbed by chlorophyll, or even if i'ts just psychological. Trees can make the difference between a slum and a nice neighborhood, all else being equal. Contractors demolish trees because they get in the way of consturction, mostly because to save as many trees as possible they would not be able to cookie-cutter the buildings and because they get in the way of the machinery and crews. The trees they plant later to meet city codes, as you point out, are a disgrace and accomplish little.

Maybe if we accepted a little expense and inefficiency in order to improve the quality of life, we would get it all back economically by encouraging people to stay in the cities instead of moving out to distant, sterile suburbs. We know that in past, when presumably, societies were less affluent, landscaping was employed to create more hospitable communities. They built to last, too. It makes you wonder if our modern attempts at economic efficiency are really good business in the long run, or just short term greed.

Just think of all those fine, comfortable, public buildings (like courthouses) built during the Depression that have lasted almost a century being replaced by hard-to-cool-and-heat metal and glass boxes that look like crap and are usually torn down just a few years after they're erected.