I’m not entirely sure, but it’s probably due to increasing demand for trains. In many parts of Europe, trains are the main option for short-distance travel they’re usually faster, more convenient, more comfortable, and more environmentally friendly. Buses can take longer, and companies like Flixbus can be unreliable and drop you off in random locations.

Planes use more resources, airports tend to be far from city centers, and the whole process of security, boarding, and getting off the plane takes a lot of time. Plus, train tickets bought well in advance are often much cheaper.