We find no impacts from nudge campaigns on aid receipt or college enrollment overall or for any subgroups

From Nudging at scale: Experimental evidence from FAFSA completion campaigns by Kelli A. Bird, et al.

Do successful local nudge interventions maintain efficacy when scaled state or nationwide? We investigate, through two randomized controlled trials, the impact of a national and state-level campaign encouraging students to apply for financial aid for college. The campaigns collectively reached over 800,000 students, with multiple treatment arms patterned after prior local interventions in order to explore potential mechanisms. We find no impacts on aid receipt or college enrollment overall or for any subgroups. We find no evidence that different approaches to message framing, delivery, or timing, or access to one-on-one advising affected campaign efficacy. We discuss why nudge strategies that work locally may be hard to scale effectively.

I understand the concept of nudging but have never been particularly enthusiastic about its use by government.   It strikes me as one more encroachment on the democratic process and the idea that citizens should shape law and behaviors through the legislative process.  Nudging comes across as the State trying to shape citizen behaviors instead.

This finding suggests that perhaps it is much ado about nothing.  Effective in limited circumstances but not scalable.  I can live with that.