I think all this hullabaloo about copyrighted patterns and being unable to make copies is a result of the big worldwide web and trying to make money before someone else comes up with a similar idea. If you look at some of the older pattern books, booklets, leaflets, etc., there is no mention of even the designer's name, much less saying the pattern cannot be reproduced. I just checked one of my Leisure Arts books "Sweaters For All Seasons" in which there are 14 patterns and not one designer name in the book.
I worked for 12 years in a law office and know the drill for copyrighted/patented items. I dare say I'd be amazed if a designer actually went to the expense and time involved to register a copyright. They couldn't sell enough patterns to cover the cost. If you want to challenge any one of them ask for proof of copyright.
Years ago sellers of patterns knew the patterns would be hand copied and passed on to other women who couldn't afford to buy the patterns themselves. Back then it was unusual to find errors in the patterns, unlike today when errors abound, even in a so-called "test-knitted" item.
For what it's worth, that's my two cents!