The majority of the human population lives below the poverty line and have probably never seen 'Citizen Kane'.
Who knows? Being poor doesn't automatically imply an inferior taste or understanding of artistic value. And with the ongoing process of humanity "going online", more people might have access to such movies. But if you want me to specify: " majority of the human population,
who has watched said movies"(...).
When we recommend movies, it's with the caveat that "if you like ----- then you will also like this movie". So we aren't recommending movies to ourselves, but instead, readers who are fans of the genre. For example, I have no interest in seeing 'The Giant Claw'.

The new Godzilla movie, yeah sure, if it's on TV.
Who is "we"? And what if there isn't a specified "genre" for that very movie? Would you still recommend it, or neglect it for not fitting your pigeonholing system?
I think most people recommend or critique movies not by following the "if you like ----- then you will also like this movie" idea (for that automatic programs already exist), but what one personally considers recommendable, based on the personal taste, which in itself is formed by your social and cultural background and upbringing, education/intellect, biological capabilities, individual expectations towards the movie based on previous experiences and as an assembly of such, your very own personality.
Even given this individuality factor, however, one does see a conformity in movie (as well as other forms of arts, entertainment, story-telling etc.) preferences among human populations across cultures and ages, most likely based on certain common aspects of human nature. One would be, to pick up Shawshank, the aspect of someone succeeding against odds, which has been attractive among us humans probably from early one (if you think of ancient fables, myths etc.). A movie nicely presenting this aspect is most certain to be favoured by many-and thus more likely to be recommended. However, the art of movies is too complex to be just limited to one example. It makes you wonder what a totally different, non-human sapient being would consider a recommendable movie...
That said, one might be more careful ranting against or rating movies when your taste in them differs significantly from others.
