Neighborhoods you’d typically want to walk in do have shade because they were all built a long time ago and there is somewhere for you to walk to. Suburban neighborhoods aren’t designed that way which is why even if there was shade there’s still nowhere to walk to.

I do agree we need more trees planted and more shade. Unfortunately a lot of space near and around places people would want to walk or bike to us instead covered in pavement for cars and parking.

We can do more than one thing at once though. We can make areas more walkable while we also plant trees. And we can flip state highway departments [1] so that they focus on serving the people and their needs instead of themselves or a small, vocal minority.

[1] Note that departments of transportation in nearly all states are highway and road transit departments first and do next to nothing w.r.t better means of transportation. Their entire context is cars and drivers and you can confirm this by looking at the budget.