The issue is that people don't know where to look for them. Tofu is usually in the produce or the dairy section, refrigerated. And soy milk is on the shelf as a rule, not in the refrigerated dairy section. It's in those aseptic packages that are shelf stable. And some of the soy companies are doing much more to get supermarket distribution.
Veggie burgers are probably the next most common.
Tempeh is a harder sell. That's not moving out nearly as quickly. But things like tofu cream cheese are in supermarkets. I see that in my supermarket now. It's the things that can masquerade as mainstream that are spreading the most rapidly.