"to play out" meaning

Question

After that, the back-seat chattering stopped. When Mr. Hampton looked into his rearview mirror he saw his daughter sending a text message on her cellphone. “Katie, you shouldn’t be texting all the time,” Mr. Hampton recalled telling her. “Your friends are there. It’s rude.” Katie rolled her eyes again. “But, Dad, we’re texting each other,” she replied. “I don’t want you to hear what I’m saying.” Mr. Hampton turned his attention back to the freeway. It’s a common scene these days, one playing out in cars, kitchens and bedrooms across the country.

1. What does the last sentence mean exactly?
2. What role plays the word "one" in the last sentence?

Answer 1

"One" is a pronoun substituting for "scene". The entire sentence is actually two complete sentences, separated by a comma. The first part:

It's a common scene

should be self-explanatory. The second part can be rephrased:

It's a scene playing out (all over).

"Playing out" is an idiomatic expression that references "scene", as in a stage performance. To play out a scene means to perform it, normally before an audience. Here it's used casually to mean "can be observed".

"Play out" also has the slight nuance of being surreal (like a staged comedy) because, to the father, their behavior makes no sense.

The entire sentence can be rephrased as:

This scene (of kids texting each other even when in the same room) can be commonly observed everywhere these days.

Answer 2

"Play out" in that sentence means "happens".

Play out

(intransitive)

to happen or turn out

Let's wait and see how things play out

Play out

Answer 3

This is a hard one for non-native speakers, but one that a native speaker would not even question. Basically, adding out to a verb adds the sense of doing something to completion:

out adv
thoroughly; completely; entirely: the children tired me out
_{TFD Online}

To "play something out" means to bring that thing to completion.

Say you're playing a game of chess and you think you're are absolutely winning the game. Your opponent might say:

You may be right. But let's play it out anyway.

Also note that a "scene" (as referenced in your bolded sentence) comes from drama, which means the playing out is as a scene in a play. Here's a comment regarding Shakespeare's play Hamlet. See if you can draw a parallel:

As fate intervenes, Hamlet gets the chance to play out his revenge without feeling the guilt or remorseful obligation for his mortal life.

In other words, he is bringing his revenge to completion.