Movie critics are sometimes asked why all movies cost the same to view,
even though some may have cost $100 million to make, and others
$500,000. It’s a reasonable question. I suppose the reasoning is that
you get about two hours of movie either way. Now 3-D has provided
exhibitors with a subterfuge to force consumers to subsidise their
upgraded projection facilities — which is deceptive, because most
theatres are upgrading to digital projectors anyway. This could be
called the 3-D children’s tax.

Do kids really care? —Roger Ebert, Spectator