>>1549744There's a lot of mountains in the center of Switzerland. There's a more direct line between Zurich and Interlaken, but it takes much longer, because it's a narrow gauge line with rack portions that has to go over a bunch of mountains.
Just the same you can go from Visp to Lugano by changing in Andermatt (around where the 120' mark is below Altdorf), but it takes ages because it's a slow narrow gauge line, and then a local train on the old Gotthard line.
Basically, everything south of Bern and Luzern (more or less) is fucked with mountains.
Pic related is a full map, railways are marked red, the thick lines are trunk lines, the thin lines are secondary lines.