"Many advocacy groups  argue that cultural institutions—which often focus on education and social progress—should align their food services with environmental and ethical values."  That's part of the answer I got from A.I. when I asked online why, when I asked the staff at the Guggenheim Museum's cafeteria what they had that was vegan, they said "Nothing."  The good news is that other institutions like the Metropolitan Museum of Art are offering plant-based dishes.