OK, again, I made that one up. Here's the real story.
The real world is simply much more complicated than the Web. And Google simply has to make its programs and services more and more smart. Consider this little fictional situation for instance. How will Google handle this dilemma?
Mr X owns a site that offers a pay-per-click program, like Google's Adsense and Adwords programs. He gets jealous of Google getting all the attention and, of course, the profit.He decides to secretly hire people to make intentional "invalid clicks" on Adsense ads on thousands of websites.
Such actions could make these things to happen:
More and more invalid clicks could result to more and more angry Adwords partners. (They certainly wouldn't want to pay for invalid clicks.)
More and more angry Adwords partners could result to less and less Adwords partners.
More and more invalid clicks could result to more and more Adsense accounts closed.
More and more accounts closed could result to more and more angry Adsense partners.
More and more angry Adsense and Adwords partners could result to less and less people using Google's Adsense and Adwords programs.
Less and less Google users could result to more and more site owners to come and use Mr X's PPCS, which could then result to more and more profit for Mr X and less and less profit for Google.
Of course, the situation I have just presented is fictional, it may never happen. (You may even say it's stupid.) But with the ongoing battle for Web supremacy, other smaller websites/companies could resort to doing such "unethical" moves.
So how can Google and its Adwords users protect themselves from click-fraud? How can (innocent) Adsense partners protect themselves from being penalised for "making invalid clicks" which they didn't do?
These are tough challenges for Google, I think. So what's the solution? Well, for me, Google simply has to outsmart the real world. But how on Earth can Google do that? I don't know, perhaps through its AI.