Again the government sticking their noses into people's personal choices and freedoms - they have no business legislating decisions that are between parent and child, husband and wife, etc.
That being said, this decision should involve three parties - the child asking for the tattoo/piercing, the parent or legal adult guiardian, and the tattoo artist/body piercer. Any reputable tattoo artist/piercer has a responsibility to talk to both the child and the parent first. They need to be reasonably comfortable and sure that the child is the one who is wanting the tattoo/piercing, and that the parent is agreeable and simply giving their permission. Then it's OK. But if there is even a hint that the child is being pierced/tattooed against their will or simply because the parent/guardian wants it done, the artist has every right/responsibility to refuse the service.