The idea of pervasive monitoring and dragnet surveillance was very much an implausible tinfoil-hat conspiracy theory in the minds of the general public until the Snowden revelations came out. Everyone knew that we were surveilling terrorists, particularly since 9/11, but they weren't aware that the NSA/GCHQ were doing things like compromising major communications platforms of domestic companies and exfiltrating and storing data indiscriminately in case it became useful in the future.