The other thing about "intellectual property" is the distinct possibility of independent invention. Even if we disallow my use of my own capital hardware to make a duplicate via some state financed mechanism, there's still a very real possibility that someone else also invented the "intellectual property" in question. Several people invented the steam engine. Several people invented the telegraph, at more or less the same time. Someone in the Bronze age seems to have invented safety pins. Algorithms get independently discovered all the time - see KMP string matching for a classic, but there's certainly a lot of others. A bunch of people discovered continuations at different times. How do we stretch the idea of property to cover all this? This seems like it will lead to trouble.
Independent invention is definitely a distinguishing characteristic, and the shakiest part of the rationale for patents. IMHO, independent invention should be a defense to patent infringement. That said, it's not really implicated in the drug industry, where the folks doing the copying don't have the resources to invent and test the drugs independently.
Conditional, restricted-use-specific licensing of real and tangible personal property is common.
You've confused possession with ownership. If you loan it to someone -- or someone steals it -- you won't find it in your pocket, you won't possess it, but you will still own it.
Ownership is a relation created in law. It is different than possession. In fact, its a meaningful concept only because it can differ from possession.
> Now, "intellectual property" is another matter all together. I can't tell is my "intellectual property" is being infringed on without a large effort to police it.
That's very much true of lots of real property (and even of tangible personal property that you don't keep in your possession). If I have real property spread around the different states -- and tangible personal property on the grounds of each of those real properties -- it takes a considerable policing effort to tell if the exclusive legal rights I have to those items which make them property are being infringed.
> I have to have a state, or some huge organization, find the infringement for me.
That's true, again, of all kinds of property in general, real property, tangible personal property, and intangible personal property other than intellectual property in general.
The tangible personal property you happen to keep in your immediate possession is actually the exception here, not the norm with property. Largely, the whole point of ownership existing as a legal relationship beyond mere possession is to enable people to have control of things that aren't under their immediate supervision all the time.
> I think that's one difference in property theft vs "intellectual property" infringement
And, in general, you are wrong. What you are pointing to is just largely true of physical property (real and tangible personal property) as of intangible personal property in general and intellectual property in particular.
> I'm not exactly sure what to call it, other than "government enforced monopoly".
Government enforced monopoly is exactly the defining characteristic of all property. So, its not a bad term to use for intellectual property, its just a mistake to use that to indicate something that is supposedly distinct about intellectual property as opposed to true of all property.
> There's a difference in both magnitude of enforcement, and type of enforcement that's necessary for "intellectual property" to exist.
There are differences in the steps taken to for enforcement between every pair of categories of property (this is just as true between tangible personal property and real property as between tangible personal property and intellectual property.)
Its these kind of distinctions that are a big part of the reason that we name different categories of property in the first place; if they were all identical, rather than subcategories of a common higher-level categories, we wouldn't need named types.