They don't want to hamper competitors... it's right there in the letter: Apple has invested considerably in measuring and modeling to get a reasonably correct v

They don't want to hamper competitors... it's right there in the letter: Apple has invested considerably in measuring and modeling to get a reasonably correct value. The part that they didn't put in the letter: Now they want to make a law to sell that methodology and model. iFootprint will presumably be announced at the wwdc just before the law takes effect.