No, you can walk around with a gun, even with it cocked and so long as you keep your finger off the trigger the likelihood of an unavoidable or unforeseen accident is still fairly low. A gun is an inert object that must be compelled to become lethal by the pressing of a trigger. A 5000 pound SUV on the other hand, by simply moving at normal driving speeds in close proximity to other people, consistently presents lethal opportunities that the driver must actively take steps to prevent from becoming realities. A gun and a car are almost precise opposites in that respect.

This is, I think, an apples:oranges comparison as you're not taking the objects' functional properties into account.

What is a gun, objectively, designed to do, in the most basic terms?

Fire a projectile when the trigger mechanism is actuated.

What is an automobile designed to do, in similar terms?

Move, when the accelerator is pressed and slow when the brake pedal is pressed.

An apples:apples comparison would be something closer to this:

You can walk around with a safely holstered gun and, barring a very unlikely malfunction or external factors, it will not go off, until the trigger is pulled. You can also walk around a safely parked car and, barring a mechanical malfunction or external factors, it will not move, unless someone presses the accelerator.

Like a computer, cars and firearms generally just do what their operator "tells" them to do.