Well, they advertise pretty well by various means, and men being men regardless of species … 
It might be pointed out that in primitive societies most women are not going to “waste” all that many unfertilized eggs. Most fertlle women with a regular partner will get pregnant within a year. Pregnancy will take up nine months; then breastfeeding the infant may suppress ovulation for up to two years after that. Assuming a fertile span of about 30 years, there thus may be only about 10 time periods within that when a woman is ovulating regularly. In societies where women are almost continuously either pregnant or breastfeeding, probably fewer than 100 ova will go unfertilized.
Infertile eggs from infertile fowl.
Some women are just naturally infertile for the same reason. The just are infertile.
S. A. Answer: No Roosters? 
Sometimes, perhaps, but fertile birds will also sometimes lay infertile eggs. This is not a general explanation.
The same reason as what?
The proximate cause of infertile eggs in laying hens, but not the reason they are so prone to lay unfertilized eggs.