My daughter loves grabbing our phones and watching whatever she can pull up on them, dialing people. If you take it away she gets upset. At first I was thinking, wow phones are very addictive on a primal level, she's addicted to just the flashy screens.
I think the flashy screen being tempting might be a little true, but then I came to a different conclusion about why she was so fascinated with the phone.
I noticed she also "changes" her stuffed animals diaper including pretending to apply rash cream, pretends to read books laying around she's seen me read, fidgets with the same household items she's seen me fidget with. That's when I realized what may be obvious to people experienced with kids - they constantly imitate the adults in their lives.
So my daughter was probably obsessed with staring at a phone because she saw her parents obsessed with staring at their phones and wanted to imitate them.
Of course this may be more relevant for very young kids moreso than teenagers, where the smart phone addictions work at a higher more cognitive level. But it did drill home the message that our children can be a reflection of ourselves so if you want to improve their lives, improve your own.