>>Still, are the interior doors more durable than the external doors?
Yes.
>> Could be easy enough to go into the attic (either with access or by force) and come down in the room in under 5 minutes.
Locate the entrance to the attic. Then the room I am in, despite not knowing the layout to the house. Then smash a hole in the ceiling. Then climb through said hole without getting stuck. Without me noticing. In under 5 minutes.
>>Still, are the interior doors more durable than the external doors?
"Yes."
I doubt this. They might be equal, but I doubt the exterior door would be weaker than the interior one. It's simply not logical.
"Locate the entrance to the attic. Then the room I am in, despite not knowing the layout to the house. Then smash a hole in the ceiling. Then climb through said hole without getting stuck. Without me noticing. In under 5 minutes."
Who said the entrance had to be located? If you can smash it down, why not up? (And who said smash? If their motive is to kill you, they may have brought tools, as I said before.) Who said you wouldn't need to notice?
The point is that there are weaknesses in any house. Maybe houses in your area aren't drywall, but attackers can adapt their tools and tactics to address whatever is common in that area. It's really not as hard as people think.