I agree with you to a point
But on the other hand, if you had a human pilot, you would have to build into the craft a means for the human to detect the difference, too. A window, video feed, laser altimeter, whatever. Giving the robot an automated way to do it would be easier/lighter/cheaper than giving a human the ability to do it.
Yes of course you would lose the ongoing variable capabilities that a human can bring to bear on all aspects of the mission. But if you can narrow the mission requirements to something that a robot can perform at all, it will always be able to perform that mission much more cheaply than a human.