Why use poka-yoke if finished products are inspected anyway?

I’m trying to understand the practical value of mistake-proofing at the workstation when a factory already inspects finished parts before shipping. If inspection catches defects, what does poka-yoke add beyond another layer of quality control?

Are there cases where a simple fixture, sensor, or process constraint prevents a problem more effectively than finding it at the end? I’d be interested in examples from manufacturing lines where the distinction is clear.