I hear you, but when we are not taken up with so much of the technology that surrounds us, we tend to notice and interact people around us on a different level.
I agree that social media can be means to meet new friends, but it also takes away a great deal from human interaction.
Judging by the cashier ... NOT MANY!

And I like people, I am used to an environment where people actually greet when they walk past you, even if you are a stranger, I dont see that as wrong or purist, I see that as natural.