They get extremely robust growers here with such a dense canopy that no other plants can thrive beneath them. Also the leaves are large, difficult to chop up for mulch or to rake up. The leaves also are resistant to composting readily. Basically they are considered a messy tree to maintain. After pruning, they grow back so fast. With all the work involved pruning a large tree, after a few cycles, the owner usually just eliminates the whole tree. You still see them ocassionally, usually left to do what they want - which is to become a monster.