Why is the escape key labelled "esc" on the Mac keyboard but as a circle with an arrow pointing out of it in menus?

I have reluctantly bought a MacBook Pro so that I can develop iPhone applications as well as Android, and was searching for this mysterious key so that I could get Xcode to autocomplete for me.

Turns out the circle with a diagonal arrow pointing out of it key is actually the escape key.

Why make things so difficult, Steve?