MacOS routinely eats 30-40 GB of HD space in Volumes/Preboot and "macOS Install Data" for god knows what. Plus even a bare bones XCode installation will cost around 20 GB, much more if you actually want to run your code on connected devices.
But of course saving disk space is not exactly #1 on Apple's priority list when the 512 GB and 1 TB disk upgrades sell at 80% margin.
But 2TB and 4TB upgrades, in addition to a cost of I think $400/$800 respectively, require you move up a CPU model as well - a HUGE increase in cost that most users can't justify through improved performance.
And before someone says that mjcrosoft doesn't go after that space: a lot of ticket automats, ATMs, Kiosk displays etc. run Windows under the hood. And 9GB times the amount of devices out there are a lot of gigabytes someone has to pay.
And even if for that usecase there is a special slimmed down version of the OS one could argue that they would profit from their main desktop OS and their main embedded OS not drifting apart.
On my 1 year old install, it's 9GB with only 4GB allocated i.e. with no hardlinks outside WinSxS. So delete stuff outside instead of messing up with this folder.
9gb doesn't seem like much but it's wasted space I get to pay for but am not able to use.
Out of curiosity, any reason you don’t just use Proton and stick with Linux?