Those are the policies of You Tube/Google, not necessarily US copyright law.

And largely because people believe the law is either (a) whatever they think it should be or (b) whatever some other random jerk on the internet told 'em it was.

1. Not distinguishing between the Supreme Court taking a case and making a decision on the merits, and the Supreme Court not taking the case. There are only a few things the Supreme Court is required to hear. Most of their cases fall into categories that they are allowed to decide if they want to take them are not. There are many more cases vying for their attention than they can handle, so they tend to only take cases that raise important issues and that have been sufficiently explored in the lower courts.

When they do not take a case, it (1) does not set any precedent, and (2) does not indicate what they think of the merits.

Yet the press often reports these rejections as if the Supreme Court decided on the merits that the appealing party was wrong.

2. Not understanding the history of the case and what the Supreme Court's decision means in the context of that history. In Campbell, for instance, one the issue of whether the parody of Roy Orbison's song was fair use, the district court said that since it was parody it was automatically fair use and granted summary judgement for the defendant. The appeals court said the fact that it was commercial and copied the whole song meant it could not be fair use.

The Supreme Court basically said they were both wrong. Parody isn't automatically fair use, but being commercial and using all of the song doesn't automatically make it not fair use. The case was sent back down for the lower courts to analyze using the guidelines the Supreme Court set out. However, the parties settled, so we never got to see how the lower courts would apply those guidelines.