This is exactly what needs to change. We need to get regulation to make this sort of collusion illegal, normalize the behavior of platform shifting software, and get developers who support this anti-consumer behavior blackballed from distribution platforms.
Recall that broadcast TV claimed viewers had no right to time shift TV shows, and music labels said ripping CDs to MP3 violated their rules, and movie studios claimed backing up DVDs was illegal. It's a shame these businesses had to go through the motions of fighting their customers but hopefully the software industry will be more self aware.
It will take a lot of work, and likely a few court cases, but we as consumers have to stand up for our rights.
What collusion here?
The apps are licensed to run on an iPhone, or on iOS. MacOS is not iOS and doesn’t run on an iPhone.
Some companies are platform agnostic. Some are not.
Graphisoft gives you a single USB key, but as far as they are concerned you can plug it into any computer with ArchiCAD and run multiple licensed instances at once on that machine. But only 1 machine at a time. Some companies allow administration of software keys and the server can keep track of how many instances are running and set a cap
MS used to isolate the Mac license from the Windows license of Office, but now they don’t care. But other companies still do that. Plenty of game companies don’t let you install the same game on multiple platforms just because you paid once.
Then there are the discounted student editions of software that are identical to the full edition except the license prevents you from legally doing anything for profit with the install.
The point is, you are buying a license to use software, and in some cares profit from the use of it. Your are not buying a copy of the software, but a license to use the copy. And as software is delivered digitally, you pay for the license, and then are presented a link for downloading the current version of the software connected to your license, as well as updates and possible future upgrades.
This is a bit different from a song or movie, where buying the physical media gave you a copy of a certain static version that you are allowed to use and archive, but not profit from.