There are fatal IO errors and non-fatal. Most of us don't care about the non-fatal case, but mainframes have the concept of "file isn't available now, load tape 12345", "file is being restored from backup, try again tomorrow" - things that your code could handle (if nothing else you should inform the user that this will take a while). There is also the "read off the end of the file" exception which in some languages is the idiomatic way to tell when you have read the whole file.

But most IO errors are fatal. It doesn't matter if the filename is not found, or the controller had too many errors talking to the drive and gave up - either way your code can do nothing.