iOS follows the game console model (even though the iPhone is a "smartphone" with additional non-game features). Games are responsible for something like 70% of iOS app store revenue, which Apple taxes via its platform fees, which are comparable to game console platform fees.
Unlicensed games are, of course, the killer app for sideloading on game consoles. IIRC free developer provisioning used to last up to a year or so (?), but Apple reduced it to a week after someone created a competing app store or web site that distributed unlicensed commercial games (as well as other software) by leveraging developer provisioning. (IIRC Sony analogously killed off Linux for PS3 once someone figured out how to leverage it to run unlicensed commercial games.)
If you pay $100/year for an official Apple Dev account I think you can still get one year provisioning. This probably won't make you or anyone on HN happy, but it does exist.