When you reset an Apple Device without removing the Apple ID, you'll be prompted in setup to enter the apple id and password. This "feature" is known as Activation lock, and it's an anti-theft system.

Activation Lock is a good anti-theft system, in fact it's too good for people's own good. People buy devices second-hand, and neither Apple nor the person that bought the device has any way of contacting the original owner to ask them to remove it. Activation lock is reducing devices to E-Waste, and is harming more people than it's helping. If Apple wants to be better for the enviroment, this is going to be one of the best ways to fix that:

I propose a system where Apple still can't see the email of the original owner, but rather has a button that will send an email to the original owner explaining the issue and giving the contact info of the person who's bought the device to them.

This feature would, for the most part, fix the terrible system that is Activation Lock. It'd help millions of people.