Obviously Netflix would have more negotiating power if there were more alternatives. Netflix has enough leverage with Apple now that they pay half what regular developers pay. The dynamics play strongly in Apple's favour. 15% (or 30% for shmoes) may be a large slice. But even if the alternative app store is free for developers,

In any case, I'm not arguing that a competitive market would not be better. I'm arguing that it takes more than a minor rule to get there. The dynamics play strongly in the platform's favour. 15% (or 30% for shmoes) may be a large slice. But, unless you take the vast majority of users with you, that will add up to less revenue.

There just isn't a whole lot of middle ground, compatibility between a world with competitive dynamic and play store's business model. To the extent that a law would be successful in creating competition, the play store business model fails. It's premised on monopolism, more or less. I mean, payment processing and such obviously exist outside of a captive market... but in a competitive market, rates probably resolve to <50% of the current rate.