1. The average worker is not using public transport as such, they are using private, mass transport for say 2/3 of their journey.

2. Your assumption is that subsidies make something cheaper. Do they? And what is the impact on other industries? All the effects should be considered.

3. The Gautrain is failing because it doesn't convince anyone to use it instead of private transport. Why? Precisely because it's not cheaper, it's not effective and it does not run on time. I don't use it often and I've had to postpone flights because of bus strikes. If you're not going to the station, you need to take a bus too.

By contrast, the European train systems really do provide mass public transport to Joe Sixpack and they do go where you want to go at a fraction of the price that your next best option would cost you. And they're not exactly public, they're mostly private-public partnerships that run for profit. See the Deutsche Bahn for more details.