Because it's not so much an issue for the direct suppliers as it is for the rest of their supply chain. GM buys from Tier 1s who integrate components from Tier 2s - finding Tier 2s that are not Chinese is not too complicated, but the problem comes when you want to trace the entire supply chain from Tier 2 to Tier N (down to raw materials) and force the Tier 2s to diversify. IOW, it's not people like Amphenol/Molex/Rosenberger that are the issue, but their respective supply chains. In many cases the Tier 2s don't have end-to-end supply chain traceability at all, in others they are stuck in NDAs with their own suppliers which they can't kick back up to the next Tier, etc. They can certainly lean on the Tier 2s to find non-Chinese sources down to Tier N for better supply chain resiliency, but it will be a slow, iterative, and costly process. It's also not clear what the final BOM delta will look like, and whether this even leaves them with a margin that they can actionably go to market on. Full disclosure: I work for a large Tier 1 that is currently involved in these discussions.