> Assuming that the laws are uniformly applied (which may not be true), they are irrelevant to the differences between people's incomes.
That's not true at all. The law has huge impacts on how things are distributed. You're making an assumptions premised on how our existing system of property law works. E.g. "If Person A invents hoverboards and everyone buys them, creating billions in economic value..." Our current system is, of course, completely arbitrary.
Say Person A invents hoverboards, then Person W00001-W10000 engineer the production design, mine the raw materials, assembles them, packs them, transports them, and sells them. Say $4 billion in economic value is created as a result.
Objectively, all we can say is that the $4 billion in economic value is the product of that combined activity. If nobody transported those products to the market, there would be $0 of economic value. Apportioning "credit" for the resulting economic value, and thus income from the proceeds, is a completely subjective process. It is no less subjective just because we do it indirectly, through a system of arbitrary property rules that leads to a particular allocation.
Our system of property and contract law gives very strong protections to: 1) people who originate the last 5% of a valuable idea; 2) owners of capital. The "inventor" of the hoverboard almost certainly had 95% of the research already done for him, he just took the idea the last step forward. Assigning him 100% of the credit in the form of a patent is, of course, completely arbitrary. Moreover, in a capital-intensive business like manufacturing it won't be the inventor of the hoverboard that makes all the revenue from it, it will be the investor that supplied the production capital. Again, that's a completely arbitrary allocation.
That is not to say that there are not utilitarian reasons to prefer a set of rules that yields one allocation rather than another. Maybe giving the patent monopoly to the 5% guy yields more overall productivity than giving it jointly to the top 5 researchers who did the other 95% of the work. Or maybe we just do it that way because its the easiest system to administer. Either way, we're mired in utilitarian arguments, and whether its "fair" to "restrict" someone is wholly irrelevant to the discussion.