My DP is a piercer of 30 years standing. He will not pierce anyone under the age of 16 without parental consent, and especially not if there's any suspicion of parental conflict as a report to the council is potentially detrimental if he does.
Before I was involved with my DP my then early teens DS pierced his own ears at school out of pure peer inspired rebellion as ear piercings werent an issue either with me or his school (nearly 20 years ago, good Lord!!). He then went on to stretch them and we had to get his "blow out" seen to professionally. He went on to badger for various facial piercings, where I drew the line firmly, having seen him rough housing with his mates and imagining the gory fallout.
As to all the other issues - whole other can of worms. Like others have said, blame good piercing practice for it not being possible. And if she tries it herself or gets it done on the sky, point out the potential for scarring and infection. In my books, too young, too immature, end of story.
As a side note, my DO pierces older teens every summer holidays with parental consent while explaining that the piercing won't be properly healed when school starts - he the spendx most of the week before school starts and into September either removing the piercing or swelling for plastic retainers as schools are throwing hissy fits.....