[davnicwil]

In my experience the majority consensus is to maintain a quiet, generally polite environment on trains and buses.

But that's precisely the problem, it only takes a very tiny minority to change this. If one group, one person sometimes, in a carriage of 50 people decides to go against this, then that's that. It's not even particularly common, but it happens, it's random, and so it's just something that must be contended with.

[svnt]

I think that is the case if the majority has or exercises little to no effective social power to enforce the norm.

The majority consensus is to desire a peaceful environment but do nothing when it is violated.

[tristor]

Correct. But the golden question is, do what? The authorities don't care. Rules and laws are rarely enforced, and when they are enforced they're done so unevenly. If you decide to take matters into your own hands, it's much more likely that you will be punished by the law than the person you were correcting. So, what do you expect people to do?

[svnt]

My point is that in established cultures there are expectations around how these situations are handled, and what you expect people to do is specific to the culture. A single disapproving grandmother can put a stop to it.

That is why it breaks down — once it is discarded in a melting pot the cultural expectations are unclear and it seems you’re at least initially dependent on the state or mob dynamics.

[9x39]

>A single disapproving grandmother can put a stop to it.

I think you have to go further upstream socially - there are people that should not be free, but are. Public transit has not just loud talking or music on phones, but the mentally deranged, babbling, even actively drug using population walking a knife's edge between erratic and aggressive behavior. From my POV it's so far past a stern stare on the US west coast that the suggestion comes across comical.

[Der_Einzige]

Create vigalantee laws that legalize “taking matters into your own hands”

https://en.wikipedia.org/wiki/Philippine_drug_war

Extremely popular and objectively reduced crime and drug usage. In portlands case, you keep weed, steroids, psychedelics, and party drugs legal and come down like hell on the society destroying stuff like fenty

China needed to do similar drastic things to get out of the slump caused by the opium wars. They call that period the “century of humiliation “ for a reason.