Is "ownership" just a byproduct of physical goods? If I say I own a record, the proof is basically in the pudding. But how do I prove I own an MP3 file? I'd probably need to do something like show a receipt for it. But then again, what if I have shown that receipt to 100 people I've sold "my" copy of the MP3 file to? With physical reality, exact duplication is difficult, and is already covered under those existing laws.
It seems like computing was big on licensing, even when tech was nascent and there wasn't clearly reams of money to be made in it, there must be a reason for it.