I don't know much about Asian train stations except in Japan but the thing is that in addition to being massive in terms of traffic, the stations are also malls.

If you go to Shinjuku station, it is hard to know what is the station and what is the shopping district. The part dedicated to transportation, like the JR platform you see in every picture is just a fraction of it. All large train stations feature some kind of shops, restaurants, etc... just like airports do, however Japan is on another level. There are full department stores in the station, some of them operated by the railroad themselves.

I think there are historical reasons to it, where private railways are also retail companies, and built stations as shopping centers, which looks like a clever idea for a city to develop its public transport infrastructure from private funds.