When it comes to voluntary identity disclosures on job applications, why does there never seem to be a “prefer not to say” option for asking if you’re Hispanic or Latino, when all the other questions have one?

In the U.S. (Massachusetts).

I’ve sent out at hundreds of job applications, and all of them
have the voluntary identity disclosures at the end. You can say “prefer not to say” for race, disability status, your sex, and veteran status, but the question asking if you’re Hispanic/Latino is always just a “yes/no” question, with no option to say you prefer not to answer. I’ve never actually seen one that lets you put “prefer not to answer” for that specific question. And it generally won’t let your application through if you don’t put an answer, even though it’s ostensibly voluntary.

So, why is asking if you’re Hispanic or Latino the one question it doesn’t let you decline to answer?