What about a law-enforced, sealed jumper under the battery? You break it with a screwdriver and a gadget permanently enters "open" mode in which original, proprietary OS performs suicide and decodes the bootloader. Hostile jailbreak is hard and won't get unnoticed, producer software is safe and advanced users can't be ignored.
Those "people" who come and go as they please include those "people" who are trying to run bots, steal information, spam etc.