The place I work at states to all employees they have voluntary holidays. Now this wouldn't be here if that was the case.
Voluntary holidays to this company means, you HAVE to select at least one holiday per holiday selection group to work, then scale the others in preference of how willing you'd be willing to work. The willingness to work has to go in order, and more than one cannot have 'will not work' that day.
Some of the employees don't even get those forms to fill out, and just get to know when holiday schedules are posted, and then told tough shit it's on you.
So yeah totally voluntary holidays, what a fucking joke.