Just this morning I saw someone take a brief pause while crossing the street to look at her phone unaware that a car was coming. She stopped in the middle! of the street. The car screeched to a halt and missed hitting her by nothing.
The thing is, most of these people are (most likely) not even looking at something important, just their social media or messaging apps.
I noticed a girl who was talking to someone on the phone. She hanged and put the phone in her pocket. Not 10 seconds later she took it out and just started scrolling while walking past me.
Obviously, it's a very bad thing when someone decides not to leave her mental cave while strolling through traffic (worse still if she's behind the wheel). I just think it's a more humanistic view than the zombie angle.