The FBI wants to catch "criminals", and they like easy backdoors. The NSA is the one interested in mass-surveilance and they usually are very good at collecting information with little to no help from corporations, seeking more direct interaction only when the scale of a particular target (say Facebook) becomes so large that they need to move their filters closer to the real data to keep up.

Usually these things start pretty innocently - you'll be approached by a local police department who has a real murderer they're trying to catch, who happens to be stalking people on your service. I've been through and heard of that kind of approach happening several times. Everyone knows the big NSA/MegaFed style visits happen as well, usually not before your CEO is hobnobbing with Senators anyways, giving keynote speeches to large globalist audiences, etc. (IE by the time they let you know, you're already part of the system anyways.) That's theory, I've only experienced the former not the latter.

Some day hopefully!

(edit: I've witnessed the FBI backdoor, not the NSA. :P)