Apple's booming business is apps.

Of each app they sell, they receive 30% and they tried to do it with in-app-subscriptions also, but the industry has protested so loud, they lowered their evil conditions.

The problem with the enterprise is, that enterprises need custom applications, eg. for healthcare and etc..

This would mean that applications can be installed without Apple knowing (eg. some sort of jailbreaking) or in other words, on these apps, Apple won't receive 30% of all the revenue.