It should have an age restriction of 18 because that is when you are an adult and can make the right choices. Unfortunately people without makeup have to show id for longer when they buy age restricted products. Because under 18 girls with makeup could look their early 20s, that's why supermarkets have a challenge 25 policy, I'm young man and this really frustrates me. People should look their natural age. It should be a criminal offence for someone under 18 attempt to buy, buy makeup or wear makeup. If caught they should face 3 months youth offenders sentence. For an adult to buy it on behalf on a child should face 2 years imprisonment. Retailers would loose there licence. Then reduce the challenge 25 to challenge 21 but you still need some margin for error even without makeup because some people just naturally look older. I don't mind challenge 21 and I like it because you got a couple years leeway but not challenge 25. People should look their natural age.
There shouldn't be any restrictions on simple items that change ones appearance, makeup does not generally show one has a hatred or prejudice towards any race, nor is it disruptive. In essence, it is innocent. Makeup has been used for quite a long period of human history too, if anything proper application should be promoted so its developed more as a skill in the early years, and one can explore it as an addition to their appearance.
I believe that there shouldn't be an age restriction for purchasing or using makeup. Products such as eyeliner and lip gloss are acceptable for children of most age. Human beings have been painting and decorating their bodies since the dawn of humanity. It would simply be absurd to place an age restriction on makeup.