I've used public transportation in several dozen different large cities in Europe and I haven't seen people talk much to strangers standing or sitting next to them. There may exist more extroverted cultures in places I have not visited but I can say that people don't talk to strangers on trains or buses anywhere in Western Europe. They don't talk much in Eastern Europe, either. I've traveled by train in Russia and Poland. This phenomenon is not particularly Finnish but maybe we are slightly more extreme in this compared to other Europeans. Despite this, I have never, and I mean never, had any difficulty finding someone to talk to on a train in Finland if I've been in a talking mood. If there is nobody near my seat who seems to be open to entertaining themselves by conversing with a stranger, I just go to the restaurant car, order a beer and sit down at or near a table where there is someone looking bored.

It varies a great deal from person to person. When I visited Lombardy in Italy fifteen years ago, I was taken by surprise by how taciturn the locals seemed. They were not the incessant chatterboxes I had imagined most Italians would be. Perhaps in the South ... but I might be in for a disappointment again. ;)