In these days, security is a serious issue unfortunately.
To be honest it's to make everyone feel more safe. Namely so family members that aren't welcome to visit, or wish to cause harm against someone's will don't get in. You'd be surprised at the rate at which family members (namely extreme religious) want to stop medical treatment at all costs even if they don't have any legal rights to do so. It's a little over kill maybe, but it's the world we live in.
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