Are you ready to be responsible and check it all the time?

I am a parent of two daughters - one 16-year-old and one who has just turned 11 years. My eldest owns a phone and has had one for the last four years (at least).
However, she has only had a “proper” phone since she turned 14 and had proved herself to be trustworthy and sensible. Now my youngest is after a mobile. In fact, she asked for one on her last birthday, last Christmas and the birthday just gone!
My head is seriously wrecked with the constant battle of phone ownership as she tells me everyone has one and that I am mean.
She also says how can she prove herself when she doesn’t have a phone. I get it and I get that she wants one, but my heart and head are telling me that a phone is not the right thing for her just now.
So, I am honestly asking, why do kids need phones? OK, I did offer my youngest a basic phone, one that would be used for calls/texts with no internet or apps available.
My idea was shot down because why would she want a 'dumb phone'? Well, I thought she wanted it for calls/texts to Mam and Dad but no, she wants it for apps and, dare I say it, social media.
Social media at 11. I can’t get my head around this.
Perhaps, my knowledge of social media dangers is a factor, but I can’t help but think she doesn’t need tonnes of apps to keep her busy. There are books for that, after all.
But I am up against a child that tells me nearly every kid in her class has a phone - a proper phone no less – some even have the latest iPhone. And I am back to my original question: why?
I can only assume parents are falling foul to the demands of their kids as I bet most don’t really want their little ones to have a mobile. And if it was just for safety, surely a basic model would do the same job? 
I am a youngish enough mum; social media is a part of my work and I am not out of touch with today's world, but maybe I am too in touch.
I read all the articles and horror stories about kids getting into trouble online. Could it happen to my kid? Although, according to my 11-year-old, she wouldn’t be that stupid because yes, we have had that conversation.
We have had many discussions on the dangers and she refutes them all saying she knows all about it.
My belief is that all parents worry about this stuff but pressures from a child can be tough. I know a phone would make my daughter the happiest kid in the world, for now anyway, but she isn’t ready for one. And here is the thing: I am not ready for her to have one.
I am not ready for the supervision required when your child owns a proper phone - the trawling for signs of misuse, cyberbullying, sexting, taunting others, inadequate discussions, online searches for unsuitable content and social media addiction.
That’s not to say my child would do some or any of those things but we can’t ignore the fact that it happens, and it happens to good parents and good kids.
I am not ready and, to be honest, I’d probably forget to check. I’d forget to follow through and then what? What if she got into something online? It may not happen but what if it did and how would I feel for letting myself and her down?
My thoughts: parents, before you hand your child a phone, are you ready to be responsible and check it? Are you going to follow through or are you going to leave a minor with one of the most powerful tools at their disposal? Giving them access to anything and anyone they like?
If your answer is no, then they don’t need a phone and, more importantly, you don’t need them to have one.
Emma Hayes is a thirty-something mum of two girls aged 16 and 10, planting her right into the teenage and tween-age years! Follow her on Twitter at @EmmaHayes25.