How do you know it was a mistake? The same incentives apply. They might be sending you the wrong thing on purpose, hoping you won't notice, so the law is there to prevent that.
Here's a post from the legal advice reddit suggesting your understanding of the law is so off point that a person can be charged with larceny for listening to you:
https://www.reddit.com/r/legaladvice/comments/68phvf/comment...