^ It's ridiculous to say you're not owed some reasonable likelihood of an advertised, above-the-title star attending a show. Yes, things happen, but to have the u/s go on for 5/8 shows a week, and have that attendance ballpark not be a fluke, and to continue advertising that star without announcing anything about absences, is abjectly dishonest.
People travel from far and wide to see broadway shows, and so even if they do refund you, there's already a potentially massive amount of money and hassle you've put in. Even those who live around the corner have arranged their schedules around it.