And Frankfurt -> Alps is not regional transport, but inter-city at least. So faster option would have been ICE and going 250km/h. More expensive though, for sure. And a seat reservation for a few euros.
150 EUR vs 9 EUR and one still had to use slow regional trains once reaching Ulm so it was not that much different time-wise to justify much higher cost. Regional Express trains I used from Frankfurt to Ulm are also pretty fast (not ICE level, but not much time lost either).
49 >> 9 but 49 << monthly ticket at any regional transportation company so one could assume most people will own it and trains will be packed again.