The entire thing is being done by an algorithm by Google and the various legal groups that scour youtube for infringement. The review process is equally automated as well. Google seems perpetually allergic to having humans involved at any point and so it continues to compound the mistake the algorithms make by making them unfixable.
That's because of the amount of content which keeps increasing. Even outsourcing to low cost countries it wouldn't be cheap to hire thousands or tens of thousands of people to review cases.
Still you need to have humans in there somewhere.
