If you want an equal relationship then go work for shares in a startup with no salary, however most workers favors certain money. Employment agreements as they look today fundamentally favors the employee over the employer, you are trading certain value "an exact amount of $$$ per month" for uncertain value "some unspecified amount work might get produced which maybe can get transformed to money in the future". If the uncertain value produced is too low then the company has no reason to continue betting on your future, so they end the agreement.