People and their weird phone habits

What's the deal with people in their 30's and younger and their weird phone habits? Here's a few weird things I've never understood:

1). People who have their phones on vibrate only. Why? It's like they don't want anyone to know they're receiving a phone call.

2). They get a call and immediately leave to go outside. I don't get this either. What are they hiding? Why must they run outside the second they take a call? What's so secretive? It's like they have this irrational fear of talking on the phone around other people. I grew up in an era when you had a phone in the kitchen or living room, when it rang you picked it up and talked regardless of who was around.

3). People will text you, and when my response is too long to text I call them and they don't answer. Like, really? You literally just texted me, I know your fucking phone is in your hand, and now suddenly you're missing my call?

Stop being so weird when it comes to phones. Turn your ringer on so you can hear your damn phone ring, take a call regardless of who's around and when I know your phone is literally in your hand because you just texted me, answer my damn call.

I don't get why the younger generation has become so odd when it comes to phones. People in their 40's and above don't do this crap. It's so weird to me.