I won't do shellac polish on anyone under 16 but I know lots of places do. I would not be insured but more important is the fact that their nails are still soft & bendy so they probably won't stay on, they fiddle and pick & potentially there could be allergy risks ahead for them.
Recently I watched a professional tutorial video for gel nails and I'm sure the daughter modelling was only 14!
In the UK minors are deemed to be under 18 so my insurer stated that I have to do a consent form and have the parent in the room with me when I carry out the treatment. This I am very happy to comply with.
When I used to teach year 10 & 11 students (so that's ages 14 - 16) VTCT stipulated that you could not teach them or carry out any treatments on them, that involved the use of sharp implements, chemicals and heat. I could though demonstrate a treatment to them using a 16+ model.
This meant that to teach them an eye lash tint, you use a thick eye cleanser to simulate the technique rather than real tint.
Paraffin wax or warm wax had to be demonstrated. Cuticle remover was also deemed to be a chemical.
These rules from VTCT are a useful rule of thumb when treating minors.
I have waxed the eyebrows of a 12 year old but I don't feel comfortable doing it to be honest.
Each child is different and pushy parents don't help, but when they come in and they've been having it done at another salon plus their friends are getting it done it's difficult to stand your ground.
At least making the parent fill in a consent form does make them think about it though and I would never do a child if they were just dumped at my doorstep with no adult with them.
I suspect there is a lot of mixed feeling on this topic out there but this is my pennyworth!