I don't think it qualifies as "theft" under that theory. It would mean that the person stealing your car nightly wasn't taking your car but making a copy of it and driving it around. If the police came over to investigate your car would still be there and the "thief" would be driving a copy.
Which is where the problem comes in right?

It's not so much stealling property but intellectual property. That's what business (and consequently lawyers) have issue with.

That's also what my ISP sent me an email about this morning stating that they would suspend my service if I didn't stop giving away Tony Hawk N64 ROM's.