The US's case against Microsoft was that they leveraged a monopoly in one field (OSes) to gain market share in another (web browsers) through unfair licensing terms. Those terms were forcing OEMs like Dell to bundle IE and place it on the home screen.
I think the US case actually paints Google, not Apple, in a bad light. Apple does not license its software to OEMs, so there's no license terms that can be unfair. Indeed, if the point of the case is "OEMs should have more freedom and flexibility" - well, Apple IS the OEM.
But Google does license to OEMs under very strict terms. For example, if I am an OEM and I want to ship Google Maps or the Play Store, I must include all the apps Google asks me to, I must make Google the default search engine for everything, I must tell Google how many devices I sell, I can't sell any other devices with custom Android, etc. This is well beyond what Microsoft did, and is the basis of one of the EU's cases against Google.
The EU case against Microsoft is a little close to Apple, but only a little. Microsoft was accused of creating "disincentives for OEMs to ship third party streaming media players, and harms competition in the market for streaming media players." The concern there was that content providers would be forced to use Microsoft's proprietary media formats.
The analogy to Apple would be very strong if Mobile Safari had lots of proprietary features, like ActiveX. But instead Apple has gone the other way, e.g. by not including Flash. It does not appear that Apple is making a play to control the web through proprietary standards.
Now if Apple made it real hard to play any content from ITMS outside of Apple products, that may be cause for concern. And they did get slapped on the wrist about ebook pricing.
Now, it can be argued that Apple has enough of a vertical stranglehold that anti-trust rules can apply. It doesn't have to be an absolute monopoly to violate anti-trust law.
And i do believe Apple has gotten a slap or two on the wrist for abusing their hold on content distribution. Ebook pricing for instance.
Were all servers, mainframes and dumb terminals counted too? Back in the nineties I'm sure those counted for something compared with PCs.
Apple has a complete monopoly on the iPhone / iPad market and that market is bigger than Microsoft's market in the 90s. You cannot change the OS without changing the hardware. You cannot change the browser without changing the OS. PCs and Windows never had such restrictions.
So what's the difference? If you answer that the PC was an open standard whereas the iPhone is Apple's own toy, I personally don't think that's fair, given that Microsoft too has built the PC market ;-)
?!? Of course they do, just like Nintendo has a monopoly on the 3DS market, and Porsche has a monopoly on the 911 market, but that's just tautological.
If you meant "Apple has a complete monopoly on the smartphone/tablet market" then a 3 second Google search will show you that this is completely false.
Microsoft dominated the Personal Computing market. Apple is dominating the iOS market which is a subset of the Mobile Device market. I can buy a mobile device and experience the social and personal benefits from dozens of players.
And bringing it back to the point at hand. The reason Microsoft got in trouble is not because they had a monopoly. But because they used that monopoly to unfairly attempt to create another monopoly when a new competitor came into the market. Safari always shipped with iOS. There was never any competition to begin with.
Also at the time web browsers were still relatively new. Today basically every device and operating system comes with one, it's expected. No one ever complained that Microsoft with shipping calculator or solitaire.
To whatever degree there might be a case against Apple (which I don't really see) there are some pretty significant differences from the Microsoft case 20 years ago.