Debatable?

So here's my deal. People always say, "Don't text on dates." Clearly that is an obvious rule.
But are you allowed to say, "Don't text while hanging out with firends?"
So texting is rude, but...isn't reading kind of rude too?
Okay. None of this makes sense, but bear with me. I know this kid who whenever they have to wait for something (long bus rides, wait for a movie, etc.) they bring a book. Which is totally fine, right? Because it is always so nice to have something to fill your time. That is, if nothing else is going on. In my opinion, it is NOT okay to just plop down in the middle of a social experience and absorb yourself in your book. And maybe it is, but when people want to talk to you and have to literally pull  your nose out of your book so they can even just say hello, that's where I draw the line.
But then I have this problem. Because some people text when they're with friends and it's totally fine with me? So what's the difference? Should I still be having an issue?
The answer is yes. Because if you text someone while nothing is going on, or there is spare time, that's fine. Just like with a book. You can pull it out if there is nothing else exciting happening. BUT if you have your full attention glued to a screen or a page, you have a problem. Seriously.
BE WITH THE PEOPLE YOU ARE WITH.
I don't care if you'd rather text or read or check your facebook or snog in the corner. But just be with the people you are with.
Clearly some people drive me up the wall.
Peace.