Eh, that's a few dozen steps removed. By that standard, every herbivore "uses" photosynthesis.
These guys (coral & lichen too) use photosynthesis much more directly, completely encapsulating the algea and supporting it internally. It's much closer to mitochondria.
I feel like this is more an issue of poor healthcare than personal choice. It seems like rather than the U.S. chosing to be opt-in, they are physically unable to give everyone the choice to opt-out.