I have had people not complete the registration for an event. They fail to click on the "confirm" button. It could be bigger, perhaps, but they THINK they are done and plan to send a check rather than pay with paypal on-line. The problem is that the registration totally goes away if that "confirm" button is not clicked. Yes it should be caught by the person receiving the check or perhaps the check does not get sent.... BUT the person arrives at the conference and they are not counted in the numbers and the registration has to be done on site, causing issues and such. The person swears they registered, but never clicked that button, so all the info is gone.