It's of course a cultural thing rather than a single unifiying rule. In the South of the United States strangers strike up conversations and I can ask people ab

It's of course a cultural thing rather than a single unifiying rule. In the South of the United States strangers strike up conversations and I can ask people about themselves without it being weird. In the North of the United States, I wouldn't bother unless I already knew someone well and if I know them well why am I asking them for? Wouldn't do it in Japan, Germany or Scandinavia; would do it many other countries.