You may own the device, but you won't have total control over every single app or its storage, because there will always be components that are crucial for proper functioning of the system or for the apps you install. If the user tinkers with those, it could potentially cause app instability or system crashes. That's why the system will protect certain files and directories from manipulation by the user (or by 3rd party apps).
Rooting a phone can give the user much more control over these things, but if the user isn't careful, they could really mess things up and make the phone unusable. Not all phones have a root exploit either -- if you want to start wading into that, the forums at XDA-Developers.com would be a better resource.
The 23 GB of space available to the user implies that of the 32 GB (I assume) your phone came with, 9 GB are taken up by the system, as well as any uninstallable bloatware the manufacturer and/or the carrier preloaded. This is standard reporting for any device, including iPhones.
Sorry if I was confusing you, but I was asking for the Storage menu in the system settings (not the Play Store app settings). So bring up the system settings, then Storage, and that's the screen I'm referring to.
And FYI, for some more perspective, there are more than 3 billion Android users globally. Compare that with, say, Bank of America, which has an estimated 69 million customers. It's a pretty big difference. And if you want to compare with Apple, keep in mind that iPhones are entirely in-house, while there are more than 1000 different Android device manufacturers (and each manufacturer has to tweak the base Android code to make it work on their hardware, as well as to give it their own little features and characteristics). So while Apple support can know immediately all of the technical details of a customer's phone, Google can't (and the individual Android device manufacturers often have terrible support, because support costs money). The closest Android comparison to iPhones would be Google's own Pixels -- and Google does have an option in Pixel devices to chat with support.