Riddle me this

Consider.

A fly has countless tiny hairs on its back and legs that detect air movement, and a viewing perception second to hardly any other creature (I said hardly because I don't know, as this is more of a rant than a well-researched post).

Baring this in mind, why on earth can't it see that our office sash window opens at the bottom, and not the top? Furthermore, when it reaches a solid pane of glass, instead of trying another part of the window, why does the stupid little moron just try that same pane a bit harder each time?

I think flies are given more credit than they deserve.