Hopefully they plant a mixture of male and female trees.
Many urban environments only plant males in an attempt to prevent debris from flowers, seeds, etc but what therefore happens is huge amounts of pollen get produced, with nowhere to go, and it causes allergic reactions among some people.
Some tree types can self pollinate of course, but others use a male female system. Another advantage beyond preventing allergies, is that these seeds and fruits which are produced can be foraged by people. This provides a small source of healthy food for people, for free. But of course, the powers that be generally don't want that...