Why Were All of the Eggs Put in One Basket?

The United Egg Producers (UEP) and the Humane Society of the United States (HSUS) announced in July that they had reached an agreement to phase in modifications to conventional battery cages over the next 15 to 18 years. The deal marks a surprising shift in position for HSUS, which had been campaigning against all caging of hens. Details of the pact remain under wraps, but it appears that the key component is the adoption of federal legislation mandating various cage changes over time. (Unfortunately, it looks as if the legislation would also include language to preempt stronger state law.) Given that it is an enormous challenge to get any measure through Congress intact - particularly a controversial one - it is curious that successful passage should form a cornerstone of the agreement. If UEP - which represents producers supplying 90 percent of U.S. eggs - sincerely supports change, why not simply require its membership to improve their own animal care standards?