That's quite a leap. I don't see how "poor people are unable to see how to provide themselves with things they want" is more likely than "people with the money

That's quite a leap. I don't see how "poor people are unable to see how to provide themselves with things they want" is more likely than "people with the money to buy things they want are more likely to do so than people who can't afford to do so". Trees are also generally seen as desirable. That desirability directly translates to increases in the value of the home, which prices out the poor. A similar effect would be seen in apartments; the trees require maintenance, maintenance takes money, so apartments with a lot of greenery are going to cost more to live in. The poor are also more likely to live in housing that they don't own. Why would a rational person dump a bunch of their own money into improving a rental property they don't own? That's assuming that their lease would even allow them to do so.