maryz I don't have teenagers but I've been one and been in a number of worrying situations by accident rather than design.
At 15 just like your daughter I was at a youth club where the police were called after some boys had torn a cigarette machine off the wall and looted it. They were long gone but the club owners and the police held all the rest of us innocents at the club because they were nasty bullies.
We were allowed to leave after the last train had gone. It was about 3 miles from home and my parents weren't on the phone so I couldn't use a call box. Even if they had had a phone, they didn't have a car.
A group of us walked home because we'd been told never to leave each other. If they hadn't been going my way I'd have asked to stay with a friend until morning. If there was no one I'd have asked the police to take me to their station because I was a vulnerable child. I was very confident about doing that kind of thing because my parents are Know Your Rights kind of people and brought me up to be one too.
We had fun walking home but my parents were worried sick until I turned up. They did hold on to the hope that they'd raised a sensible and resourceful child.
I'm sure yours are too. I'm not advocating throwing teenagers to the wolves and seeing who survives but if you give young people sensible advice like: always keep a bit of money in a safe place, try to get a cab, try to phone, never leave each other even if you've rowed, always walk rather than accepting lifts from strangers or drunk people, ask for help from an official, stay the night in a safe place then they will probably survive most things.
If all young people know how to do is to get on the mobile to their mum then they are in trouble if they don't have a mobile for any reason or God forbid, they trust the wrong person.
I do find people checking their phones, even on silent, annoying but we'll agree to differ because we're different people with different experiences 
OP: sorry for the hijack. I don't think your kids are bad. It's just planning and expectations. Hope it's good next time.