It’s not up to the OC to declassify the door as an emergency exit.
The initial DA will have required certain emergency accesses. The usual is that an emergency exit is required within a certain distance of , for instance, a garage. These exits must be maintained and are tested yearly in the fire safety report.
Additionally emergency doors are required to open out, and they cannot be locked from the inside.
So whilst owners can’t enter the garage through this emergency door, there is no reason one can’t let in the tradie by opening from inside.