Is there more room on the drivers side then passenger side? (seat install)

I've heard two theories but never a definitive, "this is the fact" answer. One is to give the driver more room in the floor area for pedals, comfort etc. The other one I've heard is to give more room in the engine bay for the steering gear and left side exhaust system. Knowing how tight the driver side is under the hood on many of these Mopars, I would tend to believe the second. Maybe a combination of both. What about cars made overseas with RH steering? Did they make any? Love to hear the final answer on this too.