Vantaa people should say hi more. I am still doing it. I was used for it on Jyväskylä where I lived before. I think it was more common there. Randomly not so many people do it in Vantaa If you don't do it first. That is what I found especially with Finnish people who lived in Capital Area long. Those who immigrated to Finland do it quite often. In student areas just like in Helsinki or Jyväskylä I feel it more international and it is lots better to get Finnish friends too.