Eskys/Alcohol at Grand Finals

What is the deal with bringing your own alcohol in to the Grand Finals this week? I've had a few people ask me already this week and I know security searches your car (which they have no right to do). So why do things change from the rest of the year just because it is a Grand Final/final?
I mean, by rights, they can't really charge you to get in either - let alone stop you from bringing alcohol in! Interested in everyone's thoughts/comments...
I mean, by rights, they can't really charge you to get in either - let alone stop you from bringing alcohol in! Interested in everyone's thoughts/comments...