There's no proof to suggest they knew otherwise. Anything stated thus far is speculation. All that's been shown as "evidence" is a slide with company logos on it and some statements from the NSA which claims to collect "Facebook" data, which could really mean anything. Plus Google openly submitted a request to allow them to publicly disclose the number, type, and scope of NSLs it receives. I have more reason to doubt the Govt than these other companies.
Also, given the name "PRISM," isn't it pretty obvious how this program worked? Think about it... What does a prism do?
Meanwhile, Verizon and ATT have been completely silent and government representatives are making up new definitions for the term perjury.
They always seem to love clever acronyms that are tangentially related to whatever it deals with, like USAPATRIOT Act is actually about how to not be a good US patriot.
Also, given the name "PRISM," isn't it pretty obvious how this program worked? Think about it... What does a prism do?
Meanwhile, Verizon and ATT have been completely silent and government representatives are making up new definitions for the term perjury.