Why Not Fruit Trees?

On public streets, I mean. If municipalities are going to plant and trim trees anyway it would seem smart to plant the kind that bear apples or oranges or avocados or peaches or nectarines, right? The fruit could be available to any member of the public that wanted to pick it. Hey, access to fresh fruit in poor communities? Jobless entrepreneurs selling produce on the corner? Sounds good to me!

Is there some reason this is a bad idea?