Step back and look at what you're arguing about.
An on-call worker that needs to drive somewhere to do their work - these aren't First Responders, these are support workers. If their employer lets them respond from home after-hours, the additional 5-10 minutes to warm the battery is a non-issue.
If they need to leave within seconds of getting the call (why I have no idea) then they could simply keep their car in a garage, protected from the weather extremes.
My mother had a friend in Pittsburgh, PA whose husband was a doctor that made house calls at all hours of the night. As you may know, Pittsburgh is a hilly area and it snows in winter. He had a heated driveway so that he could respond to house calls at anytime without worry about snowfall.
If your job has extreme response requirements, you build your life to meet those needs - it's nothing new.