It is not a legal process. It is Google's process designed to minimize their involvement to the maximum degree possible.

When some random person copyright strikes your YT account you have no rights because it isn't based on the law. Its the equivalent of someone going to the manager of Starbucks and falsely saying you are harassing them, then the manager tells you to leave or they'll call the police. One private party told another private party you are a bad person and the private party in control punished you.

If memory serves the whole system came about way back because the big media companies and record companies got together to sue YT after google acquired them. So you might say the system was designed to let purported copyright holders act arbitrarily on purpose.