--So effectively the practical difference between stealing cars and downloading pirate oses is primarily one of enforcement.--
Actually, the practical difference is pretty simple. If I steal a car, I am depriving the original owner of the property.
If I steal software, I'm depriving a faceless, soulless, underhanded company of a few bucks.
Now, does that make software piracy right or justified? Um...no. Does that mean that software piracy IS NOT STEALING? YES IT DOES.
What do you suggest, that we cut off a hand for each time you pirate a program? Is this that damaging to society in general? Somehow I don't think that it is. It's more of a white collar crime and less murder in the 1st degree.