What? Nautilus (ubuntu default file browser) finds drives wherever they are mounted and lists as their own location, as if it was windows. That includes the default mount point. Even if it wasn’t detected, it can still get to the mount point by browsing through the file system normally.
Installing software can be done via a software manager (included in ubuntu and most other distros). Software not in the manager is usually distributed as a portable binary (also common on windows) or an app image (even easier to use than an installer). Once installed, that software is the same as on windows.
Besides basic file manipulation, installing/running software, and web browsing, what else does the average user even do? All of it can be done on linux, with or without CLI.