arXiv:2503.15512v3 Announce Type: replace-cross Abstract: Modern machine learning produces models that are impossible for users or developers to fully understand -- raising concerns about trust, oversight, safety, and human dignity when they are integrated into software products. Transparency and explainability methods aim to provide some help in understanding models, but it remains challenging for developers to design explanations that are understandable to target users and effective for their purpose. Emerging guidelines and regulations set goals but may not provide effective actionable guidance to developers. In a large-scale experiment with 124 participants, we explored how developers approach providing end-user explanations, including what challenges they face, and to what extent specific policies can guide their actions. We investigated whether and how specific forms of policy guidance help developers design explanations and provide evidence for policy compliance for an ML-powered screening tool for diabetic retinopathy. Participants across the board struggled to produce quality explanations and comply with the provided policies. Contrary to our expectations, we found that the nature and specificity of policy guidance had little effect. We posit that participant noncompliance is in part due to a failure to imagine and anticipate the needs of non-technical stakeholders. Drawing on cognitive process theory and the sociological imagination to contextualize participants' failure, we recommend educational interventions.