I'm not saying this is wrong, that makes a lot of sense. But on the other hand why have I never heard of other, much more dense countries facing this problem? I just never hear of Japan, China, Germany, Taiwan, etc seeing overcrowded trains and raise their hands saying "there can't possibly be a solution!"

Yeah there's tons of work ongoing. Lots of line close to the big hubs have ongoing construction to eventually switch to 15min takt.

Improvements on various train station (new underground stations in Geneva and Luzern, extra platforms, etc.).

https://company.sbb.ch/en/railway-development/future-rail/na...

(for example, there's also lots of tram, etc. projects)

Germany's passenger rail is notoriously failing. China is big and empty compared to Switzerland so there's lots of room to build. Japan's population is stagnant, and so train use might be stagnant too. (No idea about Taiwan.)

It's not impossible, but Switzerland's geography means tunneling is involved in adding capacity which makes it very expensive. Also the beautiful synchronisation of a country-wide integrated timetable where you can reliably get between any two places in the country with connections that always make sense is a point of national pride.

Japan, Taiwan and China all added dedicated infrastructure which took a long time and cost a fortune (vs the shared tracks currently used for intercity/regional/European freight). Tokyo accepts famously absurd levels of overcrowding during peak hours. Deutsche Bahn in Germany is widely thought of a joke due to chronic underinvestment meaning on-time trains are surprising.

That said, these technical concerns have nothing to do with the 10 million proposal. It's worth asking why a camp that spent decades opposing sustainability legislation has suddenly discovered the word now that it can be pointed at immigration.