Urban trees are often appreciated mainly for the shade they provide on a hot day, but their contribution reaches considerably further: filtering airborne pollutants, absorbing stormwater that would otherwise overwhelm drainage systems, and measurably lowering the surrounding air temperature across an entire street rather than only the immediate area directly beneath their canopy.
The psychological effect is measurable too, with streets that have healthy tree cover associated with lower reported stress and even, in some studies, with lower rates of certain health complaints compared with otherwise similar streets that lack any significant greenery at all along their length.
Because trees take years or decades to mature into their full functional benefit, planting one is inherently a long-term act, a deliberate investment in a future streetscape that the person doing the planting may not personally experience in its fully grown, most beneficial form. That quiet consistency is usually the part doing the most actual work.