It's a massive violation of an individual's freedoms, but not everything has to be about privacy all the time. Your car deciding it doesn't want to drive because its sensors decided you steer too funnily impairs your freedom of movement, the privacy aspect is minor in comparison in my opinion.
I'm also not too happy about the prospect of cars, which have been proven to be hackable remotely, having yet another point where an evildoer may insert motor control inhibitions. Perhaps a shitty car will let the media console inject false data about driving behaviour to trigger the system, or perhaps a particularly bad car will allow the kill switch signal to be injected directly. Either way, if I were a highway robber it worse, I'd start investigating the wireless stacks of cars common in rural areas.
With how much data car manufacturers are already sucking out of you as a driver (https://foundation.mozilla.org/en/privacynotincluded/article...), this kill switch is such a minor thing to add to the list.