They surely have both the capability and data to thwart this type of fraud. There are only two possibilities that I can think of. One is that it's a business d

They surely have both the capability and data to thwart this type of fraud. There are only two possibilities that I can think of. One is that it's a business decision, where they know these cases may exist but they took the decision that it's not worth the extra overhead. Second possibility is that it's an oversight, essentially a "bug" in the system. Either way, it appears that Google had not yet identified this as a serious problem. I give credit to them for having a Transparency Report so that others can pick up fraud and abuse which they themselves may not have already found to have been a problem; an essential safeguard. I also view projects such as Lumen as being of increasing importance.