Iβm seeing some people say crazy numbers on Twitter.
The conditions the chickens are kept in. Normally you can buy factory farm eggs ($2-3/dozen), cage-free eggs ($3-6/dozen) where the chickens can still be kept indoors, or free-range eggs ($6-10/dozen) where the chickens get to forage in a pasture of some sort. The factory farm conditions are what causes such rapid transmission so the only farms left are the smaller ones.