It's probably an extremely small percentage of people who have anything with them in their vehicle. In this evacuation they may have grabbed water and some clothes but during normal day to day driving they have nothing. I never thought you had to be a hardcore survivalist to have water, snacks, small medical kit, rope, blanket, flashlight, change of clothes, quart of oil, basic tools, tape, etc on hand. I always had an old 12 v battery out of other vehicles or equipment in case I needed a jump.
I also kept 20 to 50 gallons of gasoline on hand with a date tag on the jugs and rotated it out every 3 months or less. Many people live in the here and now and when they have a crisis someone else needs to fix it.