I am going to give them the benefit of doubt in the case of PRISM. It is not clear whether PRISM is the result of forced/voluntary participation, or the result of vulnerabilities found in their systems. Because of the diagrams in the PRISM powerpoint mentioning some of the integration is "coming soon", I feel it is definitely not legally coerced, otherwise everyone would participate at once. Also due to the integration having varying limits from service to service tells me this not given to NSA on a silver platter. Lastly, the outright denial of these companies further tells me that they are unaware.

PRISM is the result of vulnerabilities found and purchased from hackers. And integrated together in a project codenamed PRISM. Each source has different levels of information sharing. And with Dropbox being a less integrated and more primitive resource for search, I know the entire PRISM program was a gum and shoestring project.