Anyhow, your position seems to be that if person A puts a lot of work into something and person B benefits from the fruits of that work in some way, B has somehow become indebted to A because B has entered an implicit contract, from the mere act of benefiting.
No, benefiting is not sufficient. I benefit every single day from technology and capital I don't own and from products I have never bought. I've never used an oil tanker directly and neither have I paid for it directly. Yet, I benefit from oil tankers every single day, and it's perfectly ok. What would NOT be ok is if I benefit DIRECTLY from a product without paying for it.
The problem with this principle is that it is impossible for a central authority to objectively quantify this kind of positive externality for individuals, much less enforce compensation.
But as you can see, I have never claimed you should be paid for positive externalities. Copying someone's unique mental work and using it to the detriment of their ability to profit from their own work is not a positive externality, it is piracy. Most people have no problem understanding the difference between externalities and piracy.
Example: Mike spends 10 years working on a brilliant poem and when it's finally finished he shows it to his best friend John. Without Mike's permission, John graffities the poem onto a bridge where Mary reads it from the train on her daily commute. She is so inspired by the poem that she decides to give up her job and start her own business, making her, and by extension, her husband Fred a millionaire. According to your principle, Fred is now indebted to Mike. But how much does he owe? $100 ? $100,000 $10M?. There is simply no
objective way of determining this, even if this whole chain of events was public, and even a Big Brother state would not be capable of illuminating all the complexities of social webs.
As I just pointed out, indirect benefits do not count. That's not what we're talking about.
Life isn't fair according to your definition of fairness. If it was, a heart surgeon who works 24 hour shifts and saves countless lives would make more money than a rich heiress who lives off rent and never lifts a finger. That kind of "fairness" can only function in totalitarian state. The heiress is lucky to be sitting on capital she didn't need to work for the same way the inventor of aspirin is unlucky he had to work for capital he cannot sit on.
We're not talking about mere unfairness (it's unfair that some are lucky to be born with good genes etc.), but about injustice.
As someone else put it well, the purpose of property rights is not utilitarian, the purpose of property rights is to settle disputes over who controls a finite resource.
I agree that it's not utilitarian, and as an approximation it is an ok definition of property to say that it settles disputes over who controls a finite resource (that's a utilitarian argument), but the more fundamental argument is that YOU OWN YOUR OWN LIFE. Your life is a WORK PROCESS. Every single moment of your life you have to work (through your metabolism at the cellular level, through physical labor and through mental labor). You are a work machine, and you are defined by that work. You are YOU because you create yourself and when you structure your surroundings and reality that becomes part of you. Since we humans are a social species (i.e. peacefully coexist) then it means that living as a human means to respect each other and live peacefully together. Peace is defined as to be able to have full sovereignty over your SELF (and hence also your WORK PRODUCTS). That's the fundamentals, not some arbitrary principles about settling disputes.