I only use my mobile to call/text people when I am out or for Google maps if I get lost.
My adult dc are similar but they also use Instagram and occasionally facebook.
My 14 year old uses his to call dh if he wants a lift. He has to be reminded to take it with him though.
My 11 and 10 year olds haven't got them.
I don't mind my dc having phones as long as they are not on social media before aged about 16. I really don't want them staring at screens like zombies though. And it always seems worse when there is quite a few children and they are all staring at phones. When I was that age then a big family get together or a wedding etc was a good opportunity to run around playing a game that's more fun with lots of people.
Also my 13 and 10 year old's struggle to sleep so I try and limit their screen time in the day as much as possible. Every family is different though and I know that some children need more screen time than others.