I'm sympathetic to Stallman's goals, but for some applications this presents a huge problem: if anyone can modify their car's auto emissions software, everyone

I'm sympathetic to Stallman's goals, but for some applications this presents a huge problem: if anyone can modify their car's auto emissions software, everyone can play Volkswagen and make their car high-performance and dirty as hell. Or people can extend the range of their WiFi by exceeding the legal power levels for unlicensed bands and making a frequency band unusable by their whole neighborhood. Or, modify someone's medical device's software to provide a very sneaky way of killing them. Now, there may be a way to solve these problems, but it would probably involve adding some unchangeable mechanism to limit the behavior of the device to keep it safe. But that's very difficult to do. Certifying that a fixed program has certain safety properties is difficult but possible; certifying that a new kind of design that allows users more freedom to tinker, but not too much, is much harder.