Switzerland has its act together with public transit as far as I'm aware, so the following doesn't actually apply to them. But something to note is that when trying to increase ridership the two most important things are reduced head times (ie a train shows up every 5 minutes, not every hour) and being consistently on-time. Only after those are sorted should transit look at eliminating fares. As if you eliminate fares first you're cutting into revenue that could be used to reduce head times and increase timeliness.