Dietrich Braess’s paradox shows that adding a road can worsen traffic, a lesson that echoes in logistics. In last‑mile delivery, teams chase Cost per Delivery (CPD) by packing more orders into a single trip. The math looks clean: a $60 trip serving one customer spreads cost across multiple orders, dropping the per‑order figure, and the metric appears to climb, masking deeper issues.

Initially the trade‑off appears harmless; two‑or three‑stop routes improve driver utilization while preserving promised windows. But as stops climb, delays accumulate—elevators, gate codes, parking hassles—each adding minutes. The final customer inherits the sum, so On‑Time Delivery (OTD) starts slipping even though CPD continues to improve on the dashboard. Consequently, customer satisfaction drops and refund rates rise.

The root cause is organizational silos: cost teams push CPD down, routing teams raise density, while support absorbs late‑delivery complaints. No group sees the full impact, so the system settles into a stable but inefficient equilibrium. Recognizing the divergence between cost and service metrics is the only way to avoid the hidden loss. Leaders must align incentives across teams to keep the whole system healthy.