If a movie receives a review score of 3 (of a grade on 1 to 5) it is considered ok; not bad. Compare that to if a game receives 60 (on a scale on 1 to 100), then it is considered quite bad. You can also make the exact comparison: a movie with a mean review score of 70 equals “quite good”, “above average” and most people will like it, but 70 for a game mean “just ok”, “average”.
80 equal to bad?
These assumptions are of course based on my personal observations of other people’s comments and my own readings of reviews of games and movies alike. It seems as if a game which players have been wanting to play for a long time receives “just” almost top scores, many players get angry at the reviewers with comments like “I had expected it to receive at least 9 [out of 10]” and “Just 81, that is very bad!”. The same rarely happens for movies if they receive an 8 or 9 (80 or 90).
40 is not equal to 40
On the other hand, quite a few movies which receive very low review scores still manage to become box office hits; the same is very rare for games. I can imagine a movie I have been looking forward to, and just before going to the cinema to watch it I read in the newspaper that it only got 40 (of 100) in review score, but I will most likely see it anyway, because it features my favorite actor and is set in a cool environment. Then I imagine a game I have been looking forward to; by reading its review score of 40 I immediately cancel my pre-order!
The only subjective conclusion I can make of this is that review scores of games and movies are viewed differently due to (1) the scores are “pushed” higher in the game media by either the critics themselves or, beware, the publishers[!] or (2) watching a movie is mostly a cheaper investment than a game hence people care less about review scores of movies. Since a game will in almost all instances be played more than once, you really want value for your money, therefore we “demand” higher scores before buying a game compared to when deciding to watch a movie.