The floor isn't raised. The slab for the garage and the "closet" look like 2 different pours. The garage floor is about 9" inside the door/wall and has a curb that is about 1/2" high and 1-1/2" wide. The inside slab is below the top of the curb about an inch making it a little below the garage floor.

The whole thing looks like it could be a "fix" to a design error (shown in wrong place), installer error ( put in wrong place), or "Stupid" error and maybe was a compromise to make the AHJ happy enough to let the builder finish. A hot housing market here in 2002 and very overloaded building inspectors. A lot of incompetent builders around then and unfortunately, they're still here.