[Miraste]

There aren't that many channels with over 5M subscribers. 3Blue1Brown is 706th in the world. It's insane to me that YouTube still doesn't have a manual sanity check for claims against their top ~1000 channels or so. That couldn't possibly cost much, and it would fix a PR problem that hits so often you can use it as a calendar.

[rtkwe]

The reason they don't is because they've made their own version of the DMCA takedown system but my understanding is that that system/law gives the strongest liability safe harbor if the platform just takes things down in response to takedown requests without taking any steps to validate them. The weaselly lawyer approved version is to just let the claimant and the poster duke it out with counter responses etc and just be passive.

[L3viathan]

At the very least they could trigger a real qualified human review of it immediately.

[Piskvorrr]

Costs money. (Probably not a lot, but you know the drill: to a large company, any expense is treated as a threat, no matter how small.)