There is no proper installable device driver system
Unlike Microsoft Windows, Linux has absolutely no concept of an installable device driver system.
I mean you plug something in and the appropriate driver is fetched based on USB or PCI IDs even if this sometimes takes a minute or fails.
Instead if you wonder where those Gigabytes went it is because you have
* Every possible X server
* A kernel with tweaks and loadable modules for every CPU (and I don't mean those from Intel and AMD), every motherboard and every USB device the kernel ever catered for
* Every timezone
* Every locale
* A really flaky system of boot relying on initrds that seem to get re-build several times per update so now you have hundreds of megabytes in /boot alone and the thing won't boot when these go wrong which they do