It's true that Berlin public transit has no physical fare enforcement (e.g. there are no ticket gates at subway stations), but the state operator of public transit is anything but lax on fare dodgers: the tickets are being checked randomly by undercover ticket inspectors, and every so often there's news of an inspector being violent [0]. The reality with ticket inspectors stands in stark contrast to the witty and playful online identity maintained by the BVG. Additionally, repeated fare dodging is treated as fraud by the German law and repeated offences can land you in jail [1].

[0] https://www.sueddeutsche.de/panorama/bvg-berlin-strassenbahn...

[1] https://taz.de/Haftstrafen-fuer-Schwarzfahren/!5529577/