Places Where It's Cool To Take Photos While Railfanning

Can anyone give me information for these systems if they are safe to do non-commercial photography/filming?

Subway systems of China and high speed rail
Hong Kong MTR
Japan and the Japan Rail network, as well as all private railways (subway systems included: Fukuoka, Kobe, Kyoto, Osaka, Nagoya, Saporro, Yokohama. I already know photography is allowed on Tokyo's subway system)
London Underground and Overground (buses also included)
Los Angeles metro
Singapore subway system
Paris metro

Thanks.