> No doubt Toyota decided that the non-Denso part was going to be cheaper,
> and they used it instead of the part used in Japan.
No, it has to do with "US content". The more US parts, the more they could say was US content. I think foreign manufacturers get tax breaks if they use US parts, so the more parts, the more the incentive. I'm not sure about that, but I believe it works that way.
They also avoid any tariffs imposed by the amount of Domestic content.
All I can say...glad I bought a Scion. They're ALL made in Japan...