Axl Rose of Guns N' Roses will have a constant supply of Dom Pérignon and Wonder Bread backstage. No, substitutes are not acceptable. Famous musicians can demand specific requirements. Food photographer Henry Hargreaves made a series of images of them, including Mariah Carey's Cristal with bendy straws and Lady Gaga's cheese on ice. You can view them all at the link.
Link -via Foodiggity
Although I imagine it could also be a matter of just things that they like and examples of "living the good life" but at least some of those riders are for screening purposes.