mv, cp ask anyway though bound to fail

[Dan Jacobson]

What is it about these commands that if they know they are going to
fail, they still ask anyway. Same for emacs' dired-do-copy etc.
$ whoami
jidanni
$ cp file /etc/passwd
cp: overwrite `/etc/passwd', overriding mode 0644? y
cp: cannot create regular file `/etc/passwd': Permission denied
$ mv /etc/motd /etc/passwd
mv: overwrite `/etc/passwd', overriding mode 0644? y
mv: cannot move `/etc/motd' to `/etc/passwd': Permission denied
$ uname -ro
2.6.18-3-k7 GNU/Linux