I think of it similarly to being required to wear a hard hat if you're in construction. It's not just about whether you're willing to get hit on the head, it's

I think of it similarly to being required to wear a hard hat if you're in construction. It's not just about whether you're willing to get hit on the head, it's about an employer's duty of care, and (if you just look at it cynically) the disruption to work caused by an incident that could have been prevented if someone took appropriate measures.