I don't see why not. We should be empowering end users to take care of their products, it's better for our culture, environment and wallets.
How hard would it be to provide clear and concise instructions, including a breakdown of the necessary tools? Ikea pulls it off, and people trust their products enough to sleep on them.
How was Microsoft able to make their new devices intuitively repairable without changing the form factor of the machine? The new Surface devices have all labeled screws and nothing is glued down, and the machines are outwardly identical to their predecessors.
Because a phone is an order of magnitude cheaper than a car. I trust myself to change my phone battery or screen, but definitely not enough to fix my alternator.