The problem with so many conspiracy theories (not just cover-ups / biased reporting) is that they would require culpability of an incredible number of people, many of which would have an incentive not to be involved.
For fake moon landings it would need everyone at Nasa and broadcasters as well as the Russians who would have a clear incentive to expose the lie.
Governments simply aren't so capable of being so organized. The real truth of things comes out whether that is a police or CIA operation or Watergate. There's always loose ends that can't be controlled.