Well because if a human crashes a plane, that human doesn't stick around long enough to learn from that experience and do better next time. Also the cost of a

Well because if a human crashes a plane, that human doesn't stick around long enough to learn from that experience and do better next time. Also the cost of a human crashing a plane is a bit more than a drone crashing itself, such that it's probably better to save on planes, and invest in simulators - whereas developing an accurate physics simulator for the purpose of training a drone might take more time/money than just letting it crash, and figure it out itself.