I do agree that activation lock ends up being unfair to people who buy locked devices second hand, and that something like the system you describe would be a more fair solution all around. But it seems like neither Apple nor the state Attorney Generals who were pushing for activation lock seems interested in investing the money and effort needed to implement such a system. To me, activation lock as it is implemented now seems like a huge publicity stunt at the expense of price conscious buyers who end up losing money when they get stuck with an activation locked device.