This problem goes way beyond active use of a phone.
I've noticed many people walking off sidewalks in front of a car, or doing the same in a parking lot. Some are young, wearing hoodies, but also many older folk too. 60+ years and older, most still seem to retain the basics from Grade 1 in school - Look Both Ways.
Most of this problem comes from refusing to make eye contact. Won't get into what that says about our "evolving" society now, but I believe it does tie into all the modern "communication" technology that most use - it definitely has changed behaviour, even when the phone is off.
The people I'm talking about are not using a phone at all. Of the hundreds+ I've seen, perhaps one or 3 individuals were using a bluetooth device I didn't notice, and were listening to a call w/o speaking. But I doubt it.
Walking in front of a fast moving multi-ton object w/o looking - strikes me as lemming like behaviour.
Rgds, D.