I do think the term “kill switch” sort of prompts you to envision some kind of operations center with people watching you drive and a big red button they can us

I do think the term “kill switch” sort of prompts you to envision some kind of operations center with people watching you drive and a big red button they can use to instantly disable your car, whereas the reality is likely going to be much more mundane. I imagine this will be something that beeps at you a lot, and relies on various sensors whose performance degrades over time, such that mechanically-perfect ten year old cars will occasionally become unusable until someone skilled figures out which $5 sensor is sending erratic values.