Most of the people whom I contribute to are able to work full-time on their passions through donations and make more than they would if they were traditionally employed.
What we have (in some countries) is: 1) Minimum wage: defined as the least amount legal to pay someone. 2) Living wage: loosely defined as the wage needed for minimum living standards for a given region 3) Market wage: What the market determines your value is worth based on supply/demand.
None of these are "fair" and they aren't usualy the same but sometimes can be.
Bollocks. A fair wage is a wage which is agreed upon by employee and employer, and is livable according to local cost of living. Let's not get into a semantic argument.
This is the key insight that OP is missing which makes them incorrectly think that "fair" can never be determined because it is some kind of objective goal post. It's not, it's highly subjective and local.