Our computer systems will fail, without trying. We can and should save the user from unexpected errors and lost data.
We can categorize these as: Physical, Legacy, New for Newness, Cultural, and Security,

Some gotcha corner cases are so hard to deal with, we just ignore them. We would have to add extra evaluations at many layers in the system and interact with the user, which may cause complications, but with sane defaults we can manage

Filesystem case sensitivity, character encoding, miss clicks, focus change, system lag, the cat walks across the keyboard and starts batting the touch screen, and you should have known better.