[kevinslashslash]

Because "red curry with tofu" is just called "red curry with tofu", not "vegan red curry with tofu". Same with chana masala, hummus and veggie sandwich, pasta marinara, etc. But a hamburger, "chicken nuggets", etc very much needs the "vegan" prefix to make it clear what it is, so you end up associating the word with the meat substitutes. But that doesn't mean American vegetarians only eat things that have the word vegan/vegetarian in the label.

Similarly, "gluten-free" is associated with breads, pastas, etc. Not rice or other non-imitation products.