For all you poor Australians who need to get a visa for a visit to Prague, you've got to take U4 to Arabellapark and then bus 88. Siedler Strasse 2 in Unterf hring is your destination. Because they just want to be loved for who they really are. Don't worry guys, we love you. Payment is done on an honor system.
Agents check sporadically for tickets in the trains.
Yes, there's a decent chance of getting caught and the fine is DM 60. It's a clean, safe, efficient system and it's cool to just pay your share. Ticket vending machines are at all entrances to the system. Validation machines are at the entrances to all trains and in buses and trams. S-Bahns are included on Eurail passes.