Things in the article I would like to comment on:

• In Germany, most public transport from local metro to long distance international trains do not have anything that stops people from entering the vehicles & platform. no ticket check, no turnstiles. so its pretty easy and inconspicuous to enter without a ticket.
• "Every day, hundreds of people do the same thing in the encrypted chat." - the public Telegram chat is not really encrypted, the article is just misleading here. of course Telegram uses standard encryption from user to server, but its not E2E like you would expect from the way its phrased.
• there are similar groups Telegram groups in other german cities, but many are not as active. Berlin is the only city with a dedicated app though, as far as i know.
• link to the webapp: app.freifahren.org