@Mame,
Here in Germany, no one gets arrested, too.
You pay an "increased transport charge" (60 euros) as an independent claim under civil law, if you are caught during checks. (Checks are carried out by inspectors of the respective bus/train companies, sometimes also by the federal police who's our railway police.)
In Germany, depending on the transport association, the proportion of fare evaders is estimated at between 0.6% and six percent.
However, there is also a penalty for multiple non-payment: across Germany, about 7,000 of 230,000 reported fare evaders recently served a substitute custodial sentence.
A couple of European towns offer free public transport within a municipality resp. a district, either on weekends or even all year. Others offer it for certain groups or residents get a flat-rate.
Luxembourg is the only country to have a totally free transport on buses, trams and trains for everyone, not only citizens/residents.
Incidentally, all people in Germany are entitled to free transport if they have been recognised by the competent authority as having a severe disability: a severely disabled person's ID card with a corresponding stamp also serves as a ticket for buses, trams, trains. (This includes travels to nearby foreign stations.)