But Apple gets a free pass?
For all intents and purposes Apple's iphone is the Windows equivalent in many parts of the world. If you are not on it, you do not exist. So Apple needs to be treated like the monopoly/duopoly they are.
macOS exclusive apps, linux exclusive apps, FreeBSD exclusive apps, z/OS exclusive apps, etc..
And considering the state of the art of Linux GPU Drivers, maybe using Windows will be the only feasible way to actually run Linux apps.
There is a technical / physical aspect to interoperability. If you want to swap your engine, the new engine needs to fit and mate up with your transmission (though, this is easier than you might think). If you want to run an app on your phone, it needs to be in a format the OS can use.
Then there is an extra, unnecessary, layer of political control. I absolutely can, with a bit of work, swap in a Chevy LS engine into a Ford F150. I don't have to ask Ford's permission. Chevy doesn't have to ask Fords permission. I, as a person with free will, can buy this engine and that car and combine them.
Apple totally prevents this. They do not allow you to do what you want with the device you own. For good or bad, they absolutely operate differently than other industries. At least from the consumers perspective.
But in your analogy, your VW would only allow VW gas sold by VW at VW filling stations. And the only two types of cars on the road are VWs and Fords, and each have their own filling station.
Now imagine you live in an area where only VW owns gas stations, they lobby the government and explain for the safety of the citizens they can't allow you to use any gas from anyone else, and the closest Ford station is 100 miles away, and you already own a VW.
I could tell you, "hey, you bought into the ecosystem, and you can leave any time".
And you would tell me I'm being unreasonable, and fight your local government to allow 3rd party gas stations.
There's a whole subculture of engine swaps, afaik, they tend not to use vw engines as the donors, but whatevs. You've got to have or make room, probably adapt the connection to the transmission, plus any engine control, cooling, and air/fuel. It's really not that hard, as long as there is room.