Yes, but walking and moving on wheels is oranges and apples. It would be a relevant comparison if a robot with a movement mechanism based on two feet was more efficient than a human.
> in one assignment I remember comparing the energy outputs between the human and robot equivalents of different tasks, whether or not the robot was humanoid in how it was designed
So I think the point in this context is relevant, even if it's apples to oranges.
You could say that a robotic gun is much more efficient than a human in killing, that's another easy easy comparison of different tasks where robots win, but it totally miss the point.
Then to boldly claim that humans are more efficient at anything compared to a machine, just does not follow.