For sales models, the doorknob hardware on the fire-door that separates the interior of the garage from the interior of the house (the man-door), should be installed in reverse.
Prospective homebuyers walking through the models cannot then accidently close a locked door behind themselves while entering into a garage, that also has its garage door padlocked on the exterior (not uncommon for sales models).
On one particular project, a husband and wife locked themselves inside the garage of one of the sales models when sales traffic was light. After unsuccessfully yelling for help for about 30 minutes, the husband then put his shoulder to the locked garage man-door and busted his way out, knocking the door through the door jamb.
If the hardware for this door is reversed with the finger-turned latch on the garage side of the door, and the keyed half of the doorknob on the house interior side, people are then prevented from entering the garage from the house and accidently locking themselves inside the garage.