>Seems like a really slow, cumbersome technique to monitor people

I agree. I wonder how many times they found what they're looking for?

Maybe slow and clumsy is part of the goal. It's a deliberate interruption that signals someone is paying attention. They probably have all sorts of classified network capture whatever, but that's not visible. It's the difference between your boss monitoring your email, and your boss sitting down at your desk and scrolling through your email.