They probably import live birds not eggs
Which takes several thousand dollars to do, plus an extensive process involving someone from the USDA transporting them and a quarantine process.
And they probably did it years ago, because look at the USDA posting at the bottom.
Once they go through all that, they start their own breeding line.
Though this is only a guess since I don't work there, nor am I a breeder.
I just want one pullet as a pet.
Here's a government link that was shared with me on another thread through a fellow BYC'er
http://www.aphis.usda.gov/import_export/animals/poultry_eggs.shtml
Procedures for Importing Poultry Hatching Eggs into the United States
ADVISORY: Until further notice, live avian commodities (including eggs for hatching) from the following countries or regions have been prohibited entry to the United States due to the presence of highly pathogenic avian influenza: Afghanistan, Albania, Azerbaijan, Bangladesh, Benin, Bhutan, Burkina Faso, Cameroon, Cambodia, Djibouti, Egypt, Ghana, Hong Kong, India, Indonesia, Iran, Iraq, Israel, Ivory Coast (Côte d'Ivoire), Japan, Jordan, Kazakhstan, Kuwait, Laos, Macau, Malaysia, Myanmar, Nepal, Niger, Nigeria, Pakistan, Palestinian Autonomous Territories, People's Republic of China, Romania, Russia, Saudi Arabia, South Africa, South Korea, South Sudan, Sudan, Taipei Chinese/Taiwan, Thailand, Togo, Turkey, Ukraine, and Vietnam.