The only apartment that I lived in and would consider moving back to was a 1940s constructed "solid" concrete apartment building in northern Minnesota. That thing was built to a standard that is rarely used anymore. The only thing you heard was people walking past your door.

What's the most common building material in those environments?

Perhaps this dates me.. but for me and my industry, there was a standing expectation that you would stay late and work as hard as necessary to get the job done. Thankfully, labor laws in California have changed since then, but during that time, it was an exceptionally draining experience trying to "climb the ladder," and not being able to come home and experience any sort of solace was soul crushing to me. It literally became my only motivation for a year and half was to get out of that environment to somewhere I could have space and peace and quiet with zero expectations of intrusions or interruptions.

I don't think they have ever lived in such a structure. They are probably talking about living in a two story light timber frame apartment from the 70s/80s. The walls are paper thin and you can wake up your neighbor walking in slippers to get a drink of water.

These mass timber buildings are SO much better.