Dumb take. If someone crashes their car into one of these, it can be replaced in a few days. Trees take decades to grow in ideal conditions. Between tall buildings in a city is far from ideal conditions.

Also algae is way more efficient at converting CO2 into O2; I think it’s maybe multiple times more efficient using the same amount of light.

As an emergency responder, I can say with confidence that when a car hits a tree, it’s rare that the car wins. The tree usually just shrugs it off.

Emergency responder in a big city? Trees will fuck up a car no doubt but not usually the tiny ones lining the streets of major urban centers, most I see get to be maybe 5 in across. But it may all be location dependant.