I think an ideal solution could be the manufacturer officially supports accessing the "privilege mode" with some sort of "release of liability". Customer must agree to this the first time they access, forfeiting warranty and ability to sue. Much like when people decide to unlock phone bootloader and root.
And to make all manufacturers willing to provide privilege mode to their products, I think either 1) the court makes clear statement of supporting this legally, or 2) having a supreme court precedence established for this, is required, otherwise some manufacturers would still fear the potential legal risk.