The reason they "can't" is b/c high resolution cameras and imaging would reveal the utter fakery for what it is. They couldn't get away with the sloppy set design they used during Apollo…people are more sophisticated and would demand camera pans, moving video footage, etc. They'd have to build a massive new set that wouldn't match original footage.
Or they can go on location…how can they do that? Autists would immediately discover the location by looking at rock formations and google earth…like they did w/ the Mars bullshit.
So they're completely fucked.