Let's say one opens a new movie theater in New York City that is accessible to the public. Are there any laws in New York state or the US in general that would force the cinema to adhere to MPAA ratings and age-restrict access to certain showings? Or is it all completely voluntary and there are in fact cinemas that don't care about the MPAA?
Here's a little bit of an interview with a representative from the National Association of Theatre Owners (NATO):
“The rating system is voluntary, but we strongly encourage theaters to enforce the rating age restrictions as applied to any movie,” a NATO spokesperson told theWrap.
So, yes it is completely voluntary. In the same article, an example is provided of a theatre that ignored the rating provided by the MPAA.
One major New York theater, the IFC Center, has announced that it will not enforce the NC-17 rating given to “Blue Is the Warmest Color” — and there is nothing the Motion Picture Association of America can do to make them do it.
So, theatres completely have the right to ignore the MPAA.