It's crazy to us too! Unfortunately, we don't have much say in the matter. That said, plenty of kids do still walk to school, and many do have sidewalks, although they're far from universal. The thing is that without the sidewalks you can more easily achieve:

1. Speed capture traffic cameras around school zones (nobody aside from the below likes these)
2. Contractor to manage the traffic camera
3. Kickbacks for the politicians to install the camera
4. Fines to pay the cop budget
5. Accidents to justify the above

It seems unlikely that this would have any political effect, let alone a negative one. Perpetual gun violence is an unremarkable feature of life in the United States.