Yes, report the tattooist, Flump!
I have absolutely nothing against tattoo's, but on a 15 year old it's just wrong. I'm absolutely gobsmacked that the mother consented to it, to be honest.
Surely at 15, there's a higher chance you'll regret what you had done at a later stage. I had my first tattoo at 18, and I hated it so much 5 years later, I had to save up and have it removed.
There's always a new 'trend', and whilst a tattoo to the wrist may be fashionable right now, chances are it won't be in ten years time.
Also, having one in such a noticeable place, may well affect her when it comes to things like careers.