Greeting Strangers

The other day I had a sudden urge to violate yet another social norm. To read about my first one click here. Now as some people put it, our society is prone to indifference to people they do not know. I decided to ignore this foolishness. I waved at a group of girls from a distance and when I got close enough I wished them a good day. They murmured their replies in such a way, as if they thought I was mistaking them for someone else.
"Uh, hi."
The word "Uh." A word of uncertainty. A word that screams, WHAT IS SHE DOING? and IS SHE OUT OF HER MIND? and my favorite, WHAT, WHO IS SHE, WHAT IS HAPPENING. ACT COOL. BUT WHAT DO I SAY?
"Uh, hi."
I gave them a final nod as I walked away, their suspicious eyes followed me until I opened the door to the café where I went to meet my friends.
I want to know why we are surprised when random strangers wish us a good day, or when a random person smiles at another. We have become distrustful of one another and wary of strangers. Of course we shouldn't be naïve and go around a city with a high crime rate at night to just walk around saying nice things to strangers. They might eat you up alive. All I'm saying is maybe we should take up kindness when we see it. If someone greets you, don't automatically assume they have an ulterior motive to mug you.