b) they still got all the money for the cars
       they produced, there is not a single missing

It doesn't work like that - in the event of a magical button that can replicate a car, all the cars they'll be able to produce and sell is exactly 1.

In such an event the car maker won't be able to recuperate its sunk costs, and the writing would be clearly on the wall, so such a magical car will never be produced, unless there's legislation in place that prevents people from giving away free cars.

In software or creative endeavorers, where the sunk cost is mostly measured in time spent on the task, there are always people willing to give away their work for free (having other incentives than money). Internet also makes it easier to find other people with the same interests and collaborate.

But make no mistake about it - hobbyists will never be able to create something like an Audi, or an Avatar or an Adobe Photoshop for that matter (yes, I'm a happy GIMP user, it ain't and never will be on the same level as Photoshop).

     I buy the DVD on amazon.com, but while it's 
     shipping I torrent the same movie and watch it. 
     Is it still a theft?

Yes and No, depending on the perspective - No because you already payed for the privilege of watching it, Yes because torrents are usually of poor quality, which may make you give bad reviews to people whom would otherwise watch it themselves.

Imagine you're Da Vinci, and I'm displaying a copy of Gioconda in my museum, half the size, with the hue changed, with less details and cropped, saying to people that that's just like the original Gioconda ... after all the hard work you've put, I'd imagine you'd get upset too.

On the other hand it isn't right for people to get charged multiple times for the same movie. So I guess piracy itself is as morally-wrong as these ripoffs.

    If I torrent something "getting for free" 
    is never the reason to do that.

IMHO, I'm also torrenting stuff because I want to check out what I'm buying ... people should really learn to make better demo versions and price their stuff according to the provided value.

Personally I'm sick of bad movies that lured me to see them because of a fancy trailer that exhibited non-representative traits of the movie.

Also for software, 30 days valuation periods are not enough for complex software like Office or Photoshop. Also, software like Photoshop Elements should be free of charge, or you should get some sort of refund when buying Photoshop.

This is the real problem IMHO - ripoffs.