PRISM can exist, AND they cannot have direct access to Google data. Both can be true.
There is another vector of privacy leakage here - there are also the ISPs, who I am pretty sure work alongside the government in a majorly secretive way.
I missed the pictures of the slides. That said, there are ways to target these services without involving the companies directly. Up to and including espionage itself.
One of the earlier articles discussed the government's concerns about keeping the program secret, lest they lose the cooperation of their private sector partners. That isn't a concern that they'd have if they were implementing the program through espionage.