"unless for some reason you use an iPhone, which forbids other browser engines, which is far worse than anything Microsoft ever did, but we just kinda accept it for some reason." - yes...what is that reason? How is it even possible?
For a simply objective look at the different positions of MS than and Apple now, there are three significant points that spring to my mind:
1. Apple do not have anything like the monopoly stronghold on the phone & tablet market that MS had on desktop and laptop PCs.
2. They are not (that I know of) directly using the market power that they do have to try completely block competitors. While there is no doubt some coercion going on (if you give iDevices pride of place in your store we may give you preference over others when supplies are low) there isn't the outright "stock Android and we won't give you any iDevices to sell" equivalent to MS's behaviour with regard to DRDOS/BeOS/OS2/... in the 90s.
3. They are not being deceptive about their position, like MS quietly but very deliberately scuppering DRDOS during Win3.1 development (https://en.wikipedia.org/wiki/AARD_code). Apple-land is officially a walled garden where MS were at least pretending to operate openly in a shared market.
More subjectively, whether these objective differences are enough to justify the relevant authorities not going after Apple is a matter of opinion and/or complex legal wrangling concerning the interpretation of monopoly/anti-competition/other legislation and its wording.
