[fabricexpert]

This argument does hold significant validity, unfortunately there is an irrational need to ensure that a minority are not exploiting the system, even at the cost of those who pay for the system.

For example, I think all buses in London should be free. Look around the bus and you'll see that most people aren't directly paying (under 16, over 60, on benefits) and by taking away the need to check for payment we could get people on and off the buses much faster and completely remove the need for card readers.