physical touch

My question comes as I am currently living in the U.S. and, based on experience, men who are friends (buddies, colleagues, etc.) rarely show affection to each other, especially physical touch. I am comparing it with other cultures where men do hugs a lot, kiss on the cheek, hold hands...

I'm just a curious to hear thoughts on the title subject. You see, I've had discussions with my therapist about being vulnerable. My life experiences have made true vulnerability almost impossible for me, to the point that I couldn't tell him in the moment what genuinely made me uncomfortable...