Its not just when they were built, but its also the fact that they haven't been updated since. In the US or Europe, any self respecting company (no matter how old the factory) would be controlling their equipment with fully automated PLC systems, probably monitored by a touch screen in a central control room. In Japan everyone is still using manual switches and dials

FWIW, I took the Shinkansen Osaka to Tokyo last night (15:40-18:40), my car was not more than 40% full and most of the passenger seemed to be foreigners with the railpass (like me).