Like the title says, why do females almost always cost more than males?

I know people might say it's because they produce the eggs, but I still don't get it. The male provides equal amount of genes. Both sexes have equally important genetics when breeding for recessive morphs and homo forms of codom morphs. And as for het forms of codoms, a male het x female norm produces the same offspring as a male norm x female het so I don't see any more value in the female there.

So what's the deal?