The problem is that Google does not want that messaging. If they collected money in exchange for not violating your privacy, they'd be acknowledging that what they do, is actually violating your privacy. At times, Google has even tried to use the rhetoric that providing you more relevant ads is a service to you that improves your experience on the Internet. (LOL)

Basically, the income they'd gain from offering this would pale in comparison of the reputation they'd lose (and following that, users) from admitting what they do is bad for you.