Says who you? Again if what any of you are saying was worth the price of a cup of coffee you wouldn't be able to buy a residential double cylinder deadbolt yet millions are sold and in use and they block egress FROM EVEN THE INSIDE without the proper key. All the lock in question here does is give people on the inside the ability to lock out everyone even people with a key. Fire, Police, EMS NONE OF THEM are going to have a key anyway. Go to any marginal or bad neighborhood in any big city and you will find hundreds of apartments with auxillary deadbolts, often more than one, that can only be operated from the inside. Same for damn near every commercial 'back door' entrance in america. So so much for the arguments you have been able to muster.