It's very common (even the norm, perhaps) for people to share personal details with total strangers in common places (bus/train/taxi driver/whatever) that they wouldn't share with family/friends.
Even a stranger is still a better option since they are, by definition, humans. Moreover you can be almost sure that a stranger will not sell your deepest secrets to the highest bidder or exploit that information to get something from you later.
I don't think they need their brain examined.