Loss leaders.

See "Loss leading as an exploitative practice": http://idei.fr/sites/default/files/medias/doc/wp/2012/lossle...

Everything about iOS

Apple has excluded all other browsers on iOS, requires you to buy more apple hardware to produce software for iOS, and has all of their rules around IAP and not allowing you to even link to an alternate store in many cases.

If iOS had a 90% market share in the US, I bet they'd have a lot more legal troubles

Intentionally pushing competition out of the market. If you don't have monopolistic power, totally legal.

Zero rating, like when wireless carriers don’t charge for certain bandwidth but do for others.

This actually is illegal in many countries as it is a violation of net neutrality.

I don’t remember what the current net neutrality status is in the United States but if the FCC is currently requiring net neutrality then things like zero rating would be illegal.

Exclusivity deals are commonplace.