They say "On a given day the average citizen of this big old world will be bombarded with over 20,000 messages, in the form of: signs, notices, posters and adverts. Government, corporations and the media, tell us what to do, what to think and how to feel. We say break free of the machine."
Their stickers are designed to "Make your fellow citizens look at things differently, make them think.". The "penalty fare" one is the best of the transport collection - which includes signs pointing the way to first class vs undesirables carriages and giving up your seat to drunks.
I still prefer the series of "No Talking", "No eye contact" and "No sitting" stickers, that were lurking around on the Tube a few years ago. They must have confused a fair few tourists on their journeys.