That’s part of the rub. YouTube doesn’t break copyright law if a user uploads copyrighted material without proper rights. Now, if YT was a free for all, then yeah. But given it does have copyright reporting functionality and automated systems, it can claim it’s doing a best faith effort to minimize copyright infringement.
Copilot similarly isn’t the one checking in the code. So it’s on each user. That said, Copilot at some point probably needs to add some type of copyright detection heuristics. It already has a suppression feature, but it probably also needs to have some type of checker once code is committed and at that point Copilot generated code needs to be cross-referenced against code Copilot was trained on.
Not necessarily. If it's just a small snippet of code, even an entire function taken verbatim, it may not be sufficiently creative for copyright to apply to it.
Copyright is a lot less black and white than most here seem to believe.