There is a distinction between installing something via the primary or a secondary mechanism. If someone said I just had to "install" a windows program and it turned out I had to compile it from scratch and set all the registry entries myself, I would be "astonished"(as in: The Principle Of Least Astonishment).

I fully understand that language matters and if this was an attempt by Google to de-legitimize this way of installing, that's no good. But for Christ's sake, having different names for different things is not inherently malicious.

I don't see why you'd be astonished here. The Play Store downloads the APK and installs the APK. If you've downloaded it already (eg with a browser), you just install the APK. How is that comparable to compiling from scratch and setting the registry entries yourself?

About five clicks more(than a single click) and a scary safety setting to turn off. But I didn't mean that installing an apk was as involved as my windows example. That was meant to illustrate that there are two completely different lines of action, two completely different levels of user competence at play.

Installing from the play store involves exactly zero knowledge of what an apk even is.

I want to flip the question around and ask you: How are you not seeing that there is a distinction?