Scale. It's easy to give real time stats when you're only monitoring a few hundred sites. There's a lot more data to crunch when you're trying to monitor half the web.
getclicky.com monitors over 200,000 sites and it's real time. Sure it's challenging to provide that level of service but without challenge life is dull.
I only meant to imply that providing such a feature is more work than a "few lines of code" when you're trying to monitor millions of sites in real time.
Oh, ok. I interpreted your comment to mean that no major service could pull real time analytics beacuse it's just too hard. Sure we're a lot smaller than Google but 200,000 is a pretty big number if I do say so myself.