That always a discussion. There are quite some people who are opposed to railway tracks that are below buildings or residential areas (me included) but the railway community was able to map a lot and is able to keep it currently.
Any discussion about it is often met with heavy discussion.
See also the german thread with currently 444 posts this year alone. Open Railway Map - Route in JOSM nicht editierbar/nicht angezeigt
But in fact it should not be in OSM, it should be in the OpenHistoricalMal.