This article develops a theory-driven secondary analysis of how automation-enabled job redesign affects frontline productivity in retail service operations and why the result matters for managerial planning. The analysis interprets a transaction-level field experiment conducted in four outlets of a major Singapore supermarket group, where cashiers were rotated between conventional checkout counters and scan-only/self-pay counters over 38 days. The published dataset comprises 152,246 transactions completed by 38 cashiers in a within-cashier design. In the scan-only format, the cashier specialized in scanning and packing while customer payment was shifted to self-pay kiosks. The preferred fixed-effects estimate shows that scan-only checkout increased scanning speed by 10.9%, and the broader customer service rate rose by about 21%. Mechanism tests indicate that the productivity gain is consistent with a reduction in the marginal cost of effort in the remaining human task: at conventional counters, a 1% increase in scanning speed was associated with roughly a 0.66% increase in payment time. Robustness checks further indicate that the observed gains are not plausibly explained by customer sorting, fatigue, learning, or differential assistance. Framed for management and planning research, the article supports a bounded but important conclusion: automation can improve operational performance not only by substituting for labor in one task, but also by redesigning work in a way that sharpens specialization, improves cashier-side throughput, and strengthens managerial control over service capacity.