Why will my parents not let me have a phone?

like any other kid I always asked my parents for a phone. It’s obviously something cool to show off to your friends and stuff, and obviously they say no every time. It’s understandable obviously, but now im in yr9 and everyone has one. It’s really annoying to be that one kid who has to pretend and use my mum’s phone to text my friends and stuff. I mention it to my parents and they say I can get one “when you’re married” or “you don’t need one you can use your mum’s”
I don’t see why having one is a problem, they can literally put restrictions on the time I can use it and apps I download, and also money isn’t a problem either. Getting influenced by social media isn’t a problem since they wouldn’t let me get TikTok and stuff either. They have so many reasons to say no and when I give a solution they just say I don’t need one. It’s so awkward when I’m waiting outside the school gate for ages and everyone else is just on their phones. My mum says I’ll get too addicted to it but if there’s a screen time limit to it then what’s the problem?
When I go and explain it to them that I want a phone then they just say why and to whatever reason i give they just say I could use my mum’s or something