The indicator isn't a very good system. It's really only meaningful and extremely high volumes, in the billions, and even then there are a few other alibis. But that's besides the point, because if I want to get away duping billions of gp, I would not do it on a single account. I would spread it over several to escape detection. So if the tracker only notices a bunch of increase in, say, 500M increments, I can still seriously damage the economy, yet players gaining 500M in one session really isn't THAT rare in the big scope of things.