Tell that to the script kiddies with a criminal record for "hacking" into their school's computer systems by entering "username: admin" and "password: password".
Right, because in that case you'd have a hard time convincing the court that the access wasn't intentional. You might not know the law existed, but you intended to access the system. You'd have a pretty solid defense if you ran a crawler that was crawling every website ever, and stumbled upon some secure site. In fact there are companies which does this exact thing, eg. shodan.
