Honestly, they even come with little pictures on them showing you to move your hands up and down through the jets of air, but 9 out of 10 times when I'm stood next to someone drying hands, I move mine and they just stand there doing nothing except maybe waggling their fingers below the air jets. Then they walk off, with still wet hands, wiping them on their clothes as they go and usually leaving the door handle wet.
I mean really, what don't people get about them?