Today's HS article about the increasing number of ticketless passengers caught on public transportation and the ensuing conversation about people who sometimes travel without tickets by accident made me wonder why so few public transit systems have higher fines for people who get caught often.
The only one I know of is De Lijn in Belgium.
The first offence can be punished with a rather moderate fine, the second offence within 12 months with a higher fine and any subsequent offences with much higher fines. This would hit the kind of people who habitually travel without a ticket quite hard, without placing an undue burden on people who just happened to forget to renew their tickets, etc. This probably wouldn't be very hard to implement, considering that they use social security numbers to write the fines anyway nowadays.