Just issuing a GET doesn't cause a somebody to be charged.
It's a process involving delivering specific tracking cookie along with the ad that should you end up clicking through to the intended destination gets tracked through either more cookies or tags in the URL.
>>damien+(OP)
How is that the user's problem? I don't care what the ad network does. If they are sending me links and I'm choosing to click on them, whatever happens is their own fault. I entered into no contract with this company.