Verification Codes...

I think more people have written things against these "verification codes" that many sites use to make sure you are an actual human being and not a bot... I really have no idea who came up with the idea, but what I'm sure about is that they are really annoying! But more annoying is when it makes just no sense to use them, like if you are logged in to a system that already validated you as a legal user, or that. Registering for classes for next semester I had one of those situations, I filled the courses I wanted to take next semester and it pops one of those annoying verification codes. I really wonder what is the reason to use this kind of mechanism in this case... so if anybody knows, or has an idea please let me know!!

This is a screenshot I took from the page when trying to register.