Great article @dysfunctional! Following you! :) Over sharing happens to me all the time: at the bus station, at the supermarket, on my way to work or to my daughter's kindergarten...

being ‘physically close to each other’ could trigger the impulse of oversharing.

I think it also depends on how we have approached the person. It's easier for the other to start talking if we are smiley, nice, polite and open to start a conversation (those pauses in the dialogue that we usually do). When I'm late and I don't even look properly at the person's face, I can tell that the person feels uncomfortable to start talking.

being strangers to each other gives the oversharing person a false sense of protection, because in your face he or she sees an anonymous person who might never meet again.

Never thought about this and it makes complete sense! If we don't know each other, the person sharing will think I'm not going to judge her, so she's comfortable to talk about whatever is bothering her at that time!