If Red hair is a dominant trait, why are there not more red haired people?

First, alot of blondes are bottled. There are alot of people out there that do have some red in there hair, but most colour it or it is in there as some hilites. Everybody had some degree of red, just a different mixture of it. Everyone has brown hair believe it or not. On the colour wheel, red, blue and yellow make up brown, so you will see some people have more of 1 colour than most.Hope that helps you some.

Dominance has nothing to do with prevalence.  There are lots of dominant genetic diseases, for instance, that are very very rare.

Look at it this way - if there are only a few people with a dominant trait, they're only going to have a few kids to whom they can pass that trait.  Then those few kids are only going to have a few kids.

Unless there's selection, meaning that people with the trait are more likely to survive and have children, the percentage of people with the trait is going to remain the same from generation to generation.

Google "Hardy-Weinberg equilibrium" for mathematical proof.

People color their hair. But sometimes even if it isn't completely red people may have red undertones. Like I do. My hair is naturally blonde and I color it to make it lighter and have always had red undertones. When I was a baby my hair was black and at a year old it turned red then to blonde. It really varies on the person.