It's a function of genetics and selective breeding.
Males are also cleaner than females, and I find I can sex them right out of the egg by the brightest ones, always been the males.
Black tipping is beleived to be an adaptation to allow thermal regulation as black absorbs heat, and this may be of more importance to females carrying eggs.
I've been breeding hondurensis a long time, through numerous generations. It's very hard to completely breed out black tipping in females.
When selecting young, they must be completely free of black tipping to have any hope of having nice looking adults. Black tipping always increases as they mature, therefore hondurensis look their best the day they hatch.
To avoid black tipping you might consider the purchase of Hypomelanistic specimens. There is not yet much domestic supply of these in Canada, but it wont be long. While some hypos, will get a tiny bit of tipping, they are generally extremely clean.
Here's one of my hypos
They stay this way pretty much to adulthood
below and adult pair of normals that represent 14 years of slective breeding. They have some black tipping but they don't get much nicer than this wihtout being hypos