Look at heavily unionized industries like hollywood and the writers guild for guidance. They effectively have a "minimum wage" where if you're part of the guild, you must be paid a MINIMUM of $64k for an original screenplay.

http://www.wga.org/uploadedFiles/writers_resources/contracts...

Guess how easy it is to get a job writing screenplays as a member of the guild? It's actually incredibly difficult and the vast majority of prospective writers are effectively unemployed, working jobs at coffee shops instead.

Putting a price floor on labor creates unemployment, period. The writers guild is just one microcosm of this effect.