Uh....quite often it is not "don't know how to handle friendliness", it's more of simply not wanting to engage in conversation with strangers. It is not fear or awkwardness, it is just the blissful feeling of being alone or with a friend. I personally find it incredibly rude and boorish when someone just invades my space or personal conversation and just assumes I want to talk to them. Then I am confronted with two choices 1) engage against my will or 2) look like an anti-social jerk. I usually try to thread the needle with a polite smile, one word answers, and then go back to talking my friend or staring at my phone. Again, I'm not the one who bothered innocent people minding their own business, how am I the bad guy?
One of the most flagrant violations I see often, especially at DL, is the "bossy AP" who just answers questions from another person's private conversation. A couple in front of me, literally whispering to each other, "Hey, do you want to see Fantasmic or World of Color tonight" and the eavesdropping AP just jumps right in "Well, Fantasmic starts at 8, but if you want go see both, blah blah blah" - the look on their face was priceless.
