As Vsauce explains, “deletion” doesn’t have as much to do with destroying a file as it does with removing the protections that keep non-deleted files safe. And over time, your system washes old data away like so much silt. Of course, sometime’s that’s not good enough, and then the process gets a whole hell of a lot more complicated.
Anybody have a sledgehammer I can borrow? I’ve got a little cleanup to do.