The technology used in theaters either uses dual projectors with a silver screen and polarized filters in front of each projector, or uses a single projector with a rotating polarizer to create the proper stereoscopic projection. Since these spaces typically only do 3D movies, this is just part of the way they are setup and it makes more economical sense to do a passive 3D setup.

Active 3D shutter glasses, and a compatible projector, offer excellent 3D, and it is more cost effective to do things this way. As well, this allows any screen to be used, which means you get the best screen for the room instead of a specialty screen which can actual make standard 2D movies not look their best.