[fnordfnordfnord]

>I steal your car at night, go joyriding and return it in the morning before you even know (unlawful taking without intent to permanently deprive...would you say that is not theft?

I would say that is not theft. According to my lay-person's understanding of the law, what you've described is called criminal conversion.

I also remain unconvinced of your notion that copyright infringement is theft.