That is probably the case, given the size of their operations.It's quite possible that Aramark doesn't actually prepare the meals, but might be getting them from an outside vendor.
Here is some more information on the food services they provide: "Aramark is an American food service and facilities services provider to clients in areas including education, prisons, healthcare, business, and leisure. It operates in North America and an additional 14 countries, including the United Kingdom, Germany, Chile, the Republic of Ireland, and Spain."
Some of the old AU posts made mention of the fact that they provide food to prisons and wondered how their prison food compared to flex meals. Hmmmm.