They’re just making sure you don’t sneak any beer in there because the owners found out that they have been losing a lot of money because of it.
Bingo! Every time I've gone through one of these event entrances, they only look in your bag to make sure you're not bringing food. Put a few female products on top and they'll immediately hand it back. They never look at the folding seats or blankets or other junk you're carrying in, much less do pat downs. Thank you, OBL, for this, enjoy your time at the bottom of the sea (if that's really where he is).