I believe that for police, and fire, the idea is that the employer provides the equipment (helmets, breathing apparatus, guns for self defense, etc) to reduce the danger component.
From what I understand, the border guards are claiming that they have a right to refuse dangerous work, on the grounds that the employer is not providing the tools and equipment necessary for safety.
In any job, you have the option to refuse work that is not safe. When I was a summer student working in a mine, my boss explicitly told me that no one, not even the mine manager, had the right to make me do anything that was not safe, and that I should not be shy in refusing to do it. When one of the workers suggested that we could use a 20 ft extension ladder in the bucket of his loader to reach higher up the wall, I refused. And everyone agreed with the decision.