
I agree with naiadknight. If they're going in many different directions and need to be able to contact you for a ride or to let you know that the volleyball practice is running late, then a non-smartphone might be a good idea. I don't even like the ability to text; if they need to contact you, they can call and talk real-time, or leave a voicemail.
My kids were adults before smartphones were invented. *I* didn't even have a cell phone when they were teenagers. You know what? We managed just fine, even in emergencies.
And I'm not sure it's entirely about whether you can trust them now, and not trust them when they're older. There are a lot of nasty people out there who take advantage of kids, no matter what age the kids are. Smartphones have built-in GPS and a halfway techy-intelligent stalker can use that to track down someone.
Your kids will probably think you're mean, but mine did, too (over other topics). Now that they're adults they understand good work ethics, appreciate what they have to work for themselves, and they thank me for having been a Mean Mom.
You might tell them that when they get older and demonstrate both actual NEED and responsibility, then MAYBE you'll consider getting them phones/smartphones. And conversely, phones can be taken away as punishment for infractions, AFTER they've proven they're responsible enough to have them.
You make your choices, and you live with them. In the end, you are those choices.
"Strength is the mental and physical fortitude to endure, resilience to bounce back, and force to create change, allowing you to thrive in any circumstance and through any adversity." TrPAssassin