Because the moon is still a big chunk of real estate, and we don't have anything orbiting it to take those kinds of photos. Take a look at this website:
http://www.boulder.swri.edu/~durda/Apollo/landing_sites.html
Besides, why do we need 'evidence'? We all know we went there. Just because you weren't around then doesn't mean we need to justify it to you or anybody else who missed it the first time. Do we need to prove WWII happened as well?