>How exactly? Require a government issued ID? What if it's fake? How would you validate that the ID is authentic? Even if it is authentic, how do you ensure that person has proper righgts

There is an infinite list depending on how strict you want to be. They could require government ID. They could require a notary. They could require a court order.

There will always be a balance between ease of takedown for legitimate claimants vs fighting false claims.