Derek Geldard wrote:
And wooden doors are vulnerable around the lock(s) and the wooden frames also tend to splinter under force.
Mortise locks are generally more secure but a good one with
hardened steel plates to resist drilling requires more wood to be
removed, similarly the re-inforced box staple (that the bolt
shoots into) needs a lot of wood to be removed from the frame.

However it's not particularly difficult or expensive to put a bit of
steel reinforcement in, especially adjacent to the box staple, or even a
sheet of steel over the whole door.

Owain