“Is there some reason this is a bad idea?” asks Conor Friedersdorf, about his plan to plant fruit trees on city streets. Yes, there is. Most of the fruit will be unpicked, and will fall on the ground and rot. This will result in a greatly increased burden on muncipal street-cleaning employees. If many of them roll into sewers (the fruit, not the employees), as seems likely, actual disaster could ensue.
That said, many street trees currently are fruit trees, just of a genetically modified variety that produces only very small and entirely inedible fruit. The Bradford Pear is particularly common.