I find it fascinating that prior to the Copyright Act of 1976, any work without the correct copyright notice would automatically enter the public domain.

In this case, it's interesting to see how the incentives for preventing such a mistake are skewed. It was the responsibility of the distributor to ensure the correct copyright notice, but they stood to gain when they didn't (and reportedly[1] kept all of the profits).

[1] https://www.plagiarismtoday.com/2011/10/10/how-a-copyright-m...