Being on the surface adds a lot of value for short trips in a tram (or similar). To reach the subway takes 2-4 minutes of travel down to platform level and back up. To cross the car lane to the tram station in Zurich takes 10-30s if you see the tram coming or read the digital signage, and a few minutes later you can be at your intended destination. Zurich has of course large parking garages, and if you bring your car in to the city you would leave it there and be able to hop around on the trams & buses, taking only a few minutes between your different shopping and eating destinations. I also think as a wealthy car driver you can differentiate yourself from the poor public-transport-dependents by choosing to stand on the tram, showing off your high-end branded shopping bags.