I'm sure for surgery rooms (at least), needing someone to rush in to help and having them fumble with ID cards outweighs a bad party trying to, I guess, muck up a surgery or something.
in the hospitals that i have been for visits usually the whole intensive care area and other sensitive areas were access controlled. so while the door to the actual surgery room might have been open, you are often not even allowed anywhere near.
Very rarely do you have people rushing in to surgery rooms. Despite TV dramas, most surgeries are not high risk, most surgical patients are not critically ill, and those that are tend to be pre-staffed for the risk. OR rooms are not usually locked but the surgical suite sure is. The bigger issue with the surgical suite is proper attire. ICUs are a different matter (where coincidentally I happen to be tonight). Generally all the staff you need is already on the locked side of the unit.
