Germany is introducing a €9 transit ticket that's valid for a full calendar month for all local and regional transport, I highly recommend getting this so you can zip around Berlin during your entire ClojureD stay without having to worry about having a valid ticket https://twitter.com/selfawaresoup/status/1528646329085353984
They're trying to get people back into public transit "after" COVID
It's more about making mobility more affordable since gas became very expensive and people are supposed to use public transport as an alternative to the car. It's part of a package that also lowers tax on gas. EDIT: it's all temporary for June, July and August