Google is using the same concept to how lawyers bill their clients. Most lawyers ask from an agreed upon amount to be placed into a trust account, and whenever they do something for their client they simply draw down on what is in the account. They charge for everything from sending emails (no kidding!) to pages that were photocopied on your behalf, and on top of this they kick you in the balls with an hourly rate. Google asks for you to put an amount of money into an account allocated for advertising. It is basically a licence for them to print money by drawing down on that account, and use all of that money up. With click fraud being such a major issue, you have no way of knowing how effective your advertising campaign has been. At least lawyers provide an invoice for every email sent or paper photocopied, but as to how important those costs were to resolving your matter is debateable. Google provides some statistics just to make some effort in making you feel better about how quickly your money vaporised in your advertising account. Google's whole online advertising program is a massive scam. It needs more stringent auditing processes in place. Otherwise they will wind up with the same reputation as lawyers.