Authorities are governed by laws and politicians. If police would even take a car to a call saying “a 9 year old is playing outside alone” then those norms and laws just need to be changed. It’s as simple as that.

Never mind the craziness that a neighbor would call the police when seeing a child outside (and that’s quite crazy) - if police answer that call they are reinforcing the idea that the child playing alone outside was wrong or dangerous.