https://en.wikipedia.org/wiki/Tying_(commerce)
https://en.wikipedia.org/wiki/United_States_antitrust_law
Note, keeping competitors barely operational inside a walled garden is classic Apple policy. No other company has the goodwill inertia to pull off such stunts. =3
MacOS isn't sold anymore, it's a free download for all supported Macs - meaning Apple is not "selling one product or service as a mandatory addition to the purchase of a different product", regardless of which product you think is being tied to the other (hardware or software).
I can see where you're coming from, but Apple wouldn't necessarily be in trouble due to the wording of the law. Maybe in some countries where the spirit of a law matters more than the specific wording, but we're quoting US legal definitions here, and my mental model of the US legal system has the phrasing mattering more than the intention
See also Windows and Internet Explorer.
Ford isn't getting sued either for only selling cars with Ford motors inside.
A market is the set of goods or services that are fungible substitutes for one another. If Ford and Chevy use the same kind of battery as each other but Honda and Toyota use a different kind then "battery for Ford or Chevy" is a market and "battery for Honda or Toyota" is a different market. If they each require different kinds of battery then "battery for Ford" is a separate market from "battery for Chevy", but even within those markets there can be multiple competitors, i.e. Ford isn't the only company that makes batteries compatible with Ford vehicles.
Whereas if Ford vehicles use a different kind of battery than other vehicles and there is only one company who makes that kind of battery, "battery for Ford vehicles" would be a market in which that supplier has a monopoly, regardless of whether the one supplier is Ford or someone else.
Which one of these looks like what Apple is doing?
> Ford isn't getting sued either for only selling cars with Ford motors inside.
Ford isn't only selling cars with Ford motors inside. They offer them that way, and it's a popular purchase option, but they'll also sell anyone essentially any part of the car by itself. They also don't prohibit you from taking the engine out of your Ford and putting it in a Chevy or vice versa.
More to the point, the EU have already slapped them with two separate $500m fines having repeatedly found that Apple used iOS and the App Store to break antitrust laws.
The US have a similar case hinging on all sorts of things ranging from green text message bubbles to heavily restricting access to the NFC API and affording to itself the privilege of host-card emulation via Apple Wallet.