[teddyh]

If someone made money from piracy, and this was made legal, would not market forces kick in and lower the market price to the cost of labour?

Maybe it’s the “someone else's creation” bit that bothers you? But that is begging the question! If copyright were to be eliminated, it would not be, by definition, someone else’s creation. The actual creators may have the right to be associated with (i.e. be credited as the creators of) the original work (eliminating plagiarism and making fraud even more illegal), but the work itself could be monetized in whatever way anyone sees fit, by anyone.