Maybe that people outside the us involve others more in decision making and rely on them for support. And in the US people decide things on their own and their conversations are just storytelling. Not sure if that is what the commenter was going for, just a guess
>U.S. people when talking about their own medical issues: I had this medical issue, I saw a doctor, and the cause was this.
I would put more US people in the former camp; especially when you consider that a trip to the doctor can become a surprise bill of the thousands for many.
Did you have equally intimate relationships with your US and non-US friends?
Telling someone a fact that happened in your life is not especially intimate. Like if I had a surgery or got married/divorced, I would tell basically anyone who asked. It's a vastly more intimate experience to consult with a friend - for me it would be a very close friend - about an ongoing crisis in my life. I don't usually ask casual friends for their input on my relationship problems or scary medical issues. Though if I do, that's usually part of building a closer friendship.
non-U.S. people when talking about their own medical issues: I have this medical issue, I wonder if I should see a doctor, the cause may be this.
U.S. people when talking about their own medical issues: I had this medical issue, I saw a doctor, and the cause was this.
non-U.S. people when talking about their own divorce: I am thinking about divorcing my wife/husband.
U.S. people when talking about their own divorce: We divorced last week.