> So, continuing to profit--forever--from someone's else work, at scale, without their prior consent, is fair use?

Yeah, you are right. Have you been paying your dues to the authors of your math books in first 4 grades? I think 15% of your wages as an engineer would suffice. These kids continue to profit for years, and they are so many. Gotta pot a stop to that IP theft.

In my mistake I thought copyright was about copying rights, not paying for using ideas themselves. If just being downstream from a copyrighted work is infringement even without substantial similarity, then it's more like patents that expire in lifetime + a million years.