If Windows software makes a mistake, I assume Microsoft can be sued. Like Toyota has been sued.
If Windows running in a Toyota kills someone, Toyota gets sued, not Microsoft. Microsoft makes it clear that their software is not to be used in a mission-critical application. Same goes for Linux or other software. Whoever makes it part of some device is responsible, at least unless the software manufacturer explicitly provides a warranty for that particular application.
Hardware analogy: if Boeing uses screws from Home Depot to build an airplane, who do you sue when the plane crashes? Home Depot or Boeing?