Being trapped can spell your doom.
As children, we would play with trapping people and being trapped. I remember being carried in a picnic blanket by my uncle Dave, a makeshift sack with me inside, swinging in an arc as he strode across a field one Summer long ago.
We often think of a house as something to keep things out. A house protects us from the rain and the cold, from wild animals, and from other people-- by keeping them out.
Elementary, dear Watson. That's why we live indoors.
But there are times when you really don't want to be inside your house.
When it's on fire, for example.
History's full of of burning buildings with people trapped inside. The Triangle Shirtwaist Factory. Our Lady of the Angels. 9/11.
National building standards are written with fire hazards in mind. Standards exist to ensure that occupants will be able to exit the building quickly and safely. To prevent entrapment, all egress doors require key-less operation from the interior.
I'll often find houses where all the doors to the exterior require keys from the inside. This can be deadly.
It's one thing to use a key during the day. It's an entirely different matter when it's dark, the power's been cut, and the hallway's filled with smoke.
Or if you happen to be a child, or a guest, or disoriented.
Or if the keys have been misplaced.
Be sure that all your exit doors can be opened from the inside without the use of keys, tools, or specialized knowledge.
Change your locks if necessary. It's a small price to avoid entrapment.