Yep, they do things across the spectrum. Most designers I know enjoy the variety though; otherwise they feel stagnate in their work.http://www.usa829.org/Contracts/CollectiveBargainingAgreements(CBAs)/Theatre,Opera,Dance.aspx
There ya go. Start doing the math. You won't get rich doing art. I have a feeling the designers you know also do corporate or R&R work which usually pays more.