Actually, no. They are hired to do research but not paid for it. They get a 9 month salary to teach, not for research.

They have to publish papers to get tenure but the university doesn't pay most math faculty for it.

If they want to get paid for research they apply for grants and get the max of a third more salary.

Most other departments make getting grant money a prerequisite for tenure. Math departments typically don't.

So in most math departments faculty members don't bother with grants. Usually only a minority of them do because they want more money.

They're not paid to do research.