[alexus]

I had the same problem and I think that is a characteristic of GTA SA that can not be changed. This happens me in the Burglary houses. Those interiors are empty if you contemplate them with the map editor. Then the objects are created when you enter in the game, with random pre-defined distribution (but always accordingly with the rooms). I think the idea was to use them for different purposes.

Anyway, you can also use "RemoveBuildingForPlayer" at connecting to remove unwanted stuff from those interiors.