I am not saying that rsync or cp is the right way to backup a DB, I was just giving a very crude example. I absolutely agree with the issues you're raising.
However, I'd still take recovering a DB that has been backed up by rsync/cp over a DB that's not been backed up at all. If you really can't be bothered to do it the right way, you're still better off doing something than running with no backups at all.
However, I'd still take recovering a DB that has been backed up by rsync/cp over a DB that's not been backed up at all. If you really can't be bothered to do it the right way, you're still better off doing something than running with no backups at all.