A given program having a default save location is true on any platform. The "My Documents" folder on windows is used for anything but. So many applications throw files in there it's basically useless.

With Android, application files are kept in application specific locations, while user files basically always end up in Download or Pictures, sometimes, rarely, Documents. DCIM for system camera photos.

If you need to clear an applications files, that can be done via that apps page in settings.

The only difference I can see is that on phones, default file system behaviour is designed so that it gets out of most people's way, while those of us who know how it works can still use a file explorer app just fine.

While normies rely on the default file picker showing a monolithic list of what's on their phones in chronological order, we don't have to. When that thing appears, you can find any file management apps installed from the hamburger menu, and find your files using them instead.