The problem is domestic automobile manufacturers do not manufacture their autos entirely in the US and a lot of times these domestic manufacturers ship them across the border more than once in the manufacturing process.
Take Ford's Maverick (Made in Mexico) with its $27k base price for example. How many folks do you think will be willing to pay an additional $6,750 in new Trump taxes to own that vehicle?
It is the same vehicle it was the day before it is just literally $6,750 more today.
Move the production to the USA you say. That plant where the Maverick is built builds all the Mavericks and Bronco Sports for the North American and South American continents.
It would take 10+ years to build a plant that can churn out close to half a million vehicles. What do you plan to do in the meantime for a vehicle? You better hope the one you are driving now holds up as new and used vehicle pricing will soar above pandemic era pricing.
What is going to happen is most of these big manufacturing companies are simply going to conclude it is not worth the expense to build big new plants in the US over that timeline especially when the US leader changes his mind on tariffs several times a week.
You aren't going to sink billions into projects like that where there is no stablity and your cash flow has been cut off because you can no longer sell a lot of your models in the US because people won't pay the Trump taxes on the new automobiles.
The safe bet and the highest expected value comes from simply sitting on their hands (keeping production where it is) and waiting for Trump to leave office in three and a half years (worst case) and hope he changes his mind before then when it all turns to shit. (best case). Either way it sure beats spending almost a trillion dollars to build a plant that size and then having to wait ten years for it to start producing anything.