ERSB ratings are guidelines and are not legal so the store will not get prosecuted for selling it to you, as far as im aware BBFC ratings are the only legal game ratings (or US equivilent)
I know the ESRB ratings aren't legal. I was just referring to cases where kids might get a game with an M-rating or higher, commit some sort of crime perceived to be related to the game, and then the parents want to blame the store for selling a game they consider inappropriate for their kid. The store is ensuring they are in the right with these ratings because at the end of the day, it's the parent's responsibility to make sure their kids aren't getting "mature" games/ones they wouldn't approve of.
<span style="font-family:Comic Sans MS">M-rated games require you to be 17 or older BUT don't forget that San Andreas is now an AO-rated game because of the "Hot Coffee" mini-game (which is excellent btw lol)</span>
