Personally I think that small talk is also regional. Some places small talk might be discouraged at a store while other places it might be encouraged. The same might be for the subway, a restaurant, the bathroom, etc, depending on the country or culture it may be totally ok or exceptionally discouraged.
I once went to a public swimming pool in Austria, half the pool was for nudists and the other half was for clothed persons. The restroom for clothed people was very long, but the restroom for nudists was busy but short. I ended up going to the nudist restroom and a 50+ year old naked guy walked up and started talking to me while using a pissoir. Basically he was asking why I was dressed at the nudist portion of the pool, I told him the line was shorter, he laughed, and went about his pissing.
I don't know about encouraged, but it's definitely not uncommon in some places. Small talk doesn't have to be a lot of communication either, it can be as little as basic platitudes. It's things like sitting at the bar in a pub and the guy beside you points out an amazing play on the television or it could be the person on the bus pointing out something crazy they see out the window.