<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by JS:
At some airports, it's even worse than that -- one person stares at the boarding pass and ID and then says "OK", and then later down the line, an official TSA person stares at the boarding pass and ID again!</font>
An LAX terminal and TPA come to mind. But the reason that both of these do it that way is because there are escelators and a shuttle, respectively, inbetween the initial entrance to the 'secure' area and the actual checkpoint. So they don't want you to go up the stairs/ride the shuttle and realize you haven't checked in.