That's not actually a thing. Very few trees we plant have specific male vs female plants. One of the few that does that gets brought up in this context, ginko, tends to have male trees preferred because the fruit kind of reeks. Ginkgo fruit is also toxic so you really don't want masses of it getting washed into local waterways in ecosystems the tree isn't native to - not a great time for the local wildlife. A significant supermajority of all the rest of the trees that you plant in cities are gonna have male and female flowers on the same plant or male and female structures within the same flower.
I do think you mean sex, not gender - trees don't really have a gender or gender expression. Either way, it would be rather irrelevant, as most trees planted in cities have both male and female flowers (oak, birch, most conifers), or even hermaphroditic flowers (citrus).
It's not really disputed. It's something that happened in one small place or two that people insist on repeating on the internet as if it's some universal thing.
thanks for this clarification. until today i was under the impression that they planted male trees only because they looked prettier and weren't as messy as the female ones (to reduce the cleaning bill of the local municipal)
One species of fungus (split-gill mushroom, Schizophyllum commune) has over 20,000 distinct sexes. Its spores can fertilize any of the other sexes - guaranteeing, basically, that it CAN mate with any spore NOT from its own parent.
Some plants do this by activating the male and female parts of their flowers at different times, but this strategy is way stronger.