Is fare dodging not so bad?
Not at all! Fare dodging is a crime!
§ 265a of the Criminal Code (obtaining services by fraud)
(1) Who obtains surreptitiously the service of an automat or of a telecommunications network which serves public purposes, the transport by a transportation device or admission to an event or a device with the intention not to pay the fee, will be punished with imprisonment up to one year or a forfeit if the act is not punishable under other provisions with heavier punishment.
(2) The attempt is punishable.
(3) The §§ 247 and 248a apply mutatis mutandis.
This is a delict of application, which means that the victim has to make a criminal complaint, so that the act will be prosecuted.
In practice the transport company (in Berlin S-Bahn or BVG) makes a criminal complaint normally when you got caught fare dodging three times. (This is not a generality; a criminal complaint can also be made after the first time!) The act then goes to the court, where it can lead to forfeits or, in case of repeated offences, to imprisonment.
You should think about this, especially if you are “on probation” for another offence. Because this probation can be revoked under certain circumstances, and fare dodging, as described above, is a crime under § 56f of the Criminal Code.