While the scope was not known, Trailblazer, Thin Thread and Turbulence were known about, and whistleblown about fairly shortly after their inception.
The difference between when Binney & Drake etc blew the whistle and when Snowden did is the time that had passed since 9/11.
Binney started making noise in 2002, when the public mood was "If it catches bad guys, it's all good"
Drake began making noise at the same time, and first went to the media in 2005, when the Iraq & Afghanistan wars, and the hunt for Bin Laden were still relatively well supported.
Snowden went public much later, and with much more detail, but if the first 2 (and the others who blew the whistle at the same time) had gotten media attention, the program may not have spread as far as it had by the time Snowden came along.
Governments are fairly terrible at covering up secrets, the question is whether the media or the public want to pay attention.