CORed
Penultimate Amazing
Its usually doors with decorative glass inserts. They theorize that someone will break through two layers of glass and reach in to turn the deadbolt by hand. Some worry about toddlers locking people out. Both are possible, but getting trapped inside during an emergency trumps those concerns, IMO
I once lived in a rental house that had deadbolts that required a key for the inside. I didn't lock them when I was inside; just the lock on the doorknob, because I was concerned about getting out quickly in the event of a fire.