Using South Korea’s National Health Insurance system, with its near-universal enrollment sustained over decades, this study found persistent underspending in the lowest-income quintile, a structural inequity that coverage alone failed to resolve. We suggest that the contribution by Sungchul Park and colleagues makes a compelling case for the ongoing need for comparative work that reveals the underlying mechanisms, trade-offs, and consequences of health policy to identify lessons that travel across nations.

At its foundation, public health reflects a commitment to shared, global responsibility. Comparative learning is one practical expression of that commitment. Reflecting this, JAMA Health Forum welcomes scholarship that compares health system performance across borders and advance methodological rigor in cross-national comparability.

This article features Ninez A. Ponce, director of the UCLA Center for Health Policy Research and principal investigator of the California Health Interview Survey (CHIS).