The article doesn’t say why the chips have a cost difference. The wafer cost of advanced nodes is ~$30k per wafer. Is the wafer cost different or is the yield different and hence the reason for the variance of 5-20%? All else being equal (same die size/design on same process) I suspect that a large part of the cost difference is yielded cost due to maturity of operations at the Arizona fab. Taiwan has had many years…
You can hop in a car and visit them. In the US they are across the Pacific and in a very different/inconvenient timezone. It's a 15 hour gap. 9 am in Arizona would be midnight in Taiwan. And there's the anti meridian running through that so it's a day later over there as well. And the business days barely overlap.
I bet all that adds some friction in day to day operations. Lost time, shipping delays, miscommunication, etc. There are solutions to this, of course. But I'm sure that adds complexity to an already complex business. So, limiting that overhead to just 5-20% sounds pretty good to me.