Hi, Robot

I'm getting sick and tired of people coming up to me in the street or on the internet and saying "please prove you're not a robot". What makes them think I might be a robot? What makes them think I might be a robot? What makes them, okay that's enough. And what sort of proof do they require? It's quite easy to find out if you're dealing with a ghost; you just have to check to see whether it has a shadow. The basic rule of thumb is no shadow = ghost. But with robots it's not so simple. Experience has shown that robots are most at ease when executing orders. "Robot, mow the lawn", "Robot, milk the cows", "Rocky, kill Apollo Creed" etc. But they are not so happy when asked to copy words. For example, the request below is likely to flummox them.

Please prove you're not a robot

Seems pretty straightforward to me. Could it be that the admonition "Please prove you're not a robot" puts unnecessary pressure on them?