By having acquired over the years that job protection and benefits are so cumbersome for employers that they won't hire the necessary staff on normal job contracts but make all sorts of manoeuvers to avoid the CDI, whether the employer is a corporation, a public company or a small business. That means that those not already inside will remain on the outside. In order to get the in, those already in would need to let go of some of their privileges. In the name of solidarity. But the principle of solidarity only applies for socialists when it's about taxing "rich" people or corporations.