Its funny.. up here in yorkshire its not frowned upon if you start chatting to a random stranger on the train or if you say good morning to people etc.
When I was living in London doing my undergrad it took me by suprise that it is not acceptable to talk to people on the tube, you are not allowed to make eye contact with anyone (if you do it is a threatening gesture), if someone is in distress you are meant to just walk round them, if you hold a door open for someone they frown at you and grunt.. considering the cities are meant to be where we progress, it seems that humanity is regressing.