attempted 1 tube-chat FAIL
Clearly they haven't done their research/ homework on psychology, animal behavioral biology, and social interaction.
Based on psychology, the tube (subway), elevator (lift), escalator and other public transportation all are consideration a box, outside of the rider's comfort zone.
Based on animal behavior, we humans like to form groups, small interact-able groups. Humans have done so long ago when finding allies and mates. That's how close friends are formed. Similarly, those outside of the circles are taken with caution and default as outsiders or enemies. Tiger, birds, bees, a whole lots of animals do the same (except penguins because if they don't they freeze to death).
When we force or place random strangers into the same box, it become harder to interaction both due to the comfort zone and too many people. The more we put in, the fewer the interaction because they all act as outsiders/ bystanders (psychology). If there were fewer people, there may be some interaction possible.
One exception is when those aren't strangers but known friends, then it wouldn't matter the extra tube-chatter talking with them.
Another exception would be the reason these guys do it, too friendly or those that put their guards down (beer anyone?). The only problem is the chat they gave only made the uncomfortable even more uncomfortable.
If they want to interact with random strangers, they need to lower their own guards as well as to let the stranger feel comfortable. Need an example? Get a city map and ask for directions. If you failed to get anyone to talk, either you're doing it wrong or the city doesn't need a map.
Also don't ask anything from strangers that have one of the following event them, headphones on, facebook-ing, gaming or sleeping. They are enjoying themselves, so stop poking our comfort zone.