Just to clarify for those who are reading (Gene and I spoke already)

Gene and I are talking about two different things.

When Gene says they were exempt undre the BCA, he is talking about the casinos not having to file W2Gs or 1099s.

He is not saying that the BCA made the wins tax exempt, its just that the casino didn't have to report it. (the practical effect of that is usually the same since most taxpayers aren't going to declare the win as income if there was no W2g or 1099 because they are not likely to get caught.