I don't know if the game actually takes this difference into account, but one of the biggest advantages that a trolleybus has over trams is that a trolleybus has a much easier time navigating steep streets in cities with a lot of steep hills. This of course assumes a temperate climate where the city isn't in a deep-freeze and covered with snow all winter long where the rubber tires of a trolleybus aren't going to work too well.

I haven't visited San Francisco, CA in over 20years, but definitely remember all those Muni trolleybusses which seemed to be everywhere. A tram with typical steel wheels on steel tracks would lack the traction to climb those steep streets, and the old-fashioned cable cars are simply too expensive to operate compared to trolleybusses.