It is likely that their tracking systems are working just fine from their perspective. The customer is paying for all of the bytes that go back and forth from malicious port scans, ping sweeps, and the like. This might not show up on your gee-whiz windows app that tracks your pc's usage and its possible that this may not even show up on the south side of your cabls/dsl router but you can bet that your DSLAM/Cable head-end is measuring every byte, rejected or otherwise.
Over the course of a month, this can mean significant data transferred that you never see as "traffic".
What strikes me most about this story is the ATT response. True this is not wireless.
2% of users use 20% of the bandwidth, so they claim that it is only fair to charge. Which is fine.
However the price mentioned is actually what really hits me. $10 for 50GB bandwidth. True its over inflated, BUT the price is not so bad. 20 cents per gigabyte seems like a major profit margin however when comparing to verizon's $10 for 1-3gb (can't remember) per month for the chrome notebook wireless internet service the prices are pretty good. Granted the price is for broadband.
What I think is that we can use these numbers to justify that ATT & Verizon are going nuts when it comes to pricing their wireless & wired caps.
Over the course of a month, this can mean significant data transferred that you never see as "traffic".