I imagine one reason the contract isn’t worded that way is because it would make it look as if Google didn’t (or wouldn’t) have any control over click fraud, and this would make advertisers reluctant to maintain their current level of ad spend. The “mystique” of Google is to make people think they are capable of doing great things with mounds of data, and even though they have admitted they cannot determine whether every click is fraudulent, they have left open the issue of how much fraud they can actually detect (and either refund or shut down the source of the fraud). So there are advertisers out there who believe that someday, Google will figure out a way to eliminate almost all of the fraud, so rather than reduce their spend, they maintain (and even increase it), so as not to lose their competitive advantage. Some advertisers don’t even pay much attention to their campaigns; they are allocated budget (as they were in traditional media), and are at liberty to spend all of it, despite fraud. Some say they are not worried about fraud (because there is fraud everywhere); some say they don’t have time to worry about fraud. I don’t think they realize that the Internet architecture as currently constituted is particularly susceptible to this type of fraud.

“I don’t really understand how these law suits have any merit.”

Perhaps they don’t. But they reveal that Google did not do an appropriate job of guarding against a kind of fraud that was well understood in Internet engineering circles until they were sued. Google has claimed that the company was too small to deal with the problem when it first surfaced. I find this claim questionable, in light of other things the company has claimed about how resources were allocated at the time, and about the general level of intelligence and engineering acumen they claim.