The reason why it's like that now is as nibburra said below vvvvv Quality control. They set up the ad revenue for members who update often and have a decent following and don't show any sign of stopping any time soon so that they put their money into something that's reliable. It's pointless to set up ad revenue for a comic that updates whenever it feels like it and only has a small handful of followers (because the followers are where they get most of the ad revenue support from and such).
I'm sure when Tapastic becomes a lot bigger and has more funds, they will consider ad revenue for a larger amount of people, but for now that's just how it is for the sake of quality control and reliable content.
Do you mean monitor traffic for your own comic? You can do that already by going into your dashboard and clicking on the Stats button next to the comic you want to know about. It'll give you a graph showing the rate of comments/shares/likes you've gotten over the past 30 days, as well as a table showing the stats of each individual comic and how many comments/shares/likes each one got. It's a helpful tool if you like seeing those kinds of numbers /nod nod
As for those with Ad Revenue, there is the Creator Portal that's only accessible by those who are a part of it, and that allows them to track their CPM and all that jazz. I'm by no means an Ad Revenue person (yet /snickers) but they do answer these questions over in their FAQ section.
