I understand it happens a lot, but why? do these people just not pay attention to the fact that they are runing out of rope? Or do they not look down and see that their rope isn't long enough? I know I'll just rapel to the end and jump, thats a great Idea...
One of my partners who is strong, smart, and competent did this exact thing. He was climbing in Zion and it had gotten dark. The guidebook said the rap was 55m but was actually like 70m. He rapped off two 60's and went right off the end. Took a bad fall and got fucked up. Could have been avoided by a little more prudence, but, shit, it happens to the best of us.