I think it's not only in your city but mostly everywhere the elderly people get indulged in a conversation quite easily becasue they despise loneliness. They want someone to talk to becasue they are not much fond of the Tech things in which they would bury their heads in, unlike those younger generations who want to talk lurking behind the hood of Facebook, Instagram and kilogram :D
Beside that, the younger generation thinks a lot before starting a conversation(I am talking about face-to-face!) like what would s/he think, is it appropriate to talk and so on...whereas the old generation, doesn't think much. If they find someone sitting or standing near or beside them, they try to take the first step by asking their name and other things(that's different thing that you might not be comfortable with all they ask! ). Because they don't want to sit silent as it is boring.
Beside that, let's imagine, there is a lady standing beside me and I approached her and tried to talk about weather, gardening, flower, life and so on, then she might get freaked out and would think I am hitting on her and will feel uncomfortable with my questions because I am a stranger, but... when the elderly people approach for a conversation, they don't think of this "flirting thing" because they have already passed that phase:D
I don't know whether my assessment makes any sense or not, but I think these might be some reasons, if not the main reason.