They’re for making short, local trips more affordable in a country that has a lot of people struggling with fuel and inflation, and for encouraging drivers to consider transit instead more often, and long-distance trips to the sea shore and mountains are a nice side benefit that is a pleasant thing to discuss when we all feel like there’s a shortage of pleasant things to discuss.
That they’ll make local transit uncomplicated for visitors (no trying to work out where to buy a given city’s tickets, or exactly which fare you need for a particular subway ride!) is also a nice incidental, and I, a taxpayer here, will be happy to see tourists using them, but that’s not why the Bundestag is spending 2.5 billion EUR on this.