There’s something worrisome in last week’s lawsuit against Dunkin’ Donuts, challenging the fast-food chain’s practice of charging for non-dairy coffee additives and not doing the same for cow’s milk and its cousins. The scholar in me is skeptical of the central claim that charging extra for soy or almond milk violates the Americans with Disabilities Act, but I’m more troubled by the lawsuit’s bizarre theory of how markets work.

Takeout coffee is a multi-billion-dollar business, dominated in the US by what are known as the Big Three: Starbucks Corp., McDonald’s Corp. and Dunkin’ Brands Group Inc. Activists argue that upcharges for non-dairy alternatives hurt human health and the environment (and, as with so much else these days, might be racist). The lawsuit alleges that by demanding a higher price for vegan coffee additives, Dunkin’ is discriminating against customers sensitive to lactose.