As the U.S. weighs investments in autonomous vehicles and air mobility against traditional rail, new analysis reveals a staggering trade-off: While AVs promise efficiency gains of 50-60% per trip, they may eliminate 100+ daily incidental human encounters per commuter. Drawing on sociology and AI-modeled scenarios, this piece examines how evaporating 'weak-tie' interactions could erode social capital and cost individuals up to $15,000 annually in lost opportunity and health impacts.