Truth is most of those ratings are arbitrary and done so without the reviewers actually playing through the games. You should do your own research as a parent regardless of the rating, especially now a days.
ESRB ratings are voluntary, the developers determine their own rating based on the ESRB's criteria.
Despite that I don't think I've ever bought a game that was inaccurately labelled.
@garlog Yes and no. Legally, there is not a requirement for the publisher to have the game rated by the ESRB--however, the vast majority of retailers and distributors require titles to have an ESRB rating prior to putting it on the shelf/up for sale. So while you technically do not have to have the game rated... it will be very difficult for a publisher to get their game on a shelf without it. Now, there are things like the Steam library for example where that is not required but then you're seriously limiting your avenues for retail. It's a Catch 22 situation.
Despite that I don't think I've ever bought a game that was inaccurately labelled.