The problem is that that is too much business for individual creators to be bothered with. It is not a matter of whether they can literally do it if they behaved as a rational, rent-seeking Homo Economicus, but whether it's actually on their minds to do business first and not just act on their emotions and run away from the problem altogether, leaving money on the table. For artists, the latter is far more likely to be the case. We should not blame human beings for being flawed and fitting into our arrangement of society poorly.