Then I guess we should include every study participant as an author across all disciplines. 200 participant study in psychology? 200 authors on the paper.
Not necessarily? The difference is that the people flipping the coins are not just experimental subjects, they're actually implementing the experimental protocol.
The kinds of participants you're talking about are not just left off the paper out of lack of interest. It's often the ethically preferable option. They often have a vested interest in remaining unnamed for privacy reasons, and derive no tangible benefit from being listed as authors.
A big author list isn't totally unheard of. The paper where they announced the discovery of the Higgs boson had an author list that spanned 8 densely-packaged pages.
