Too cool to talk first? A question for everyone.?

Why do people feel like they are cool when they don't approach others first? I know this must seem like a rhetorical question but it really bothers me. I am not a person that bugs out when someone doesn't say hi first but its so freaking annoying. I wish people would stop slobbing their own knob and just get over themselves. I'm always the person to walk up and hug someone and all of the sudden they're just cool and comfortable as pie. Before that though they'll see whoever and just stare at them and wait. Why? Why do YOU think people have something to prove by acting completely reclusive till someone barks up their tree?