Because humans are short and medium term. Then ten to fifteen years it would take to shift even a small portion of manufacturing back to the US is 1/3 of an American's working life. That's not even considering the cost to every day Americans that will lose their jobs and have to completely uproot their lives.
Then imagine just how much investment it will take to onboard manufacturing, then imagine just how much political leverage those who can offer manufacturing investments will have and what concessions they will be able wring out of the federal government to make those investments. There are legitimate pushes happening, more than a dozen White House meetings in two months, for corporation run cities free from state or federal regulations. Trump has spoken about his desire to have more than 10 "Freedom Cities" created during his presidency.
None of these investments will happen without massive subsidies, like the tariffs and port fees, socializing the risks while privatizing the profits generated from these investments. Why should most Americans care if they get a $55k/year manufacturing job in 2030 if it cost them a $50k/year port job in 2025?
On top of the fact that America's economy isn't exactly built to handle much of the manual labor-intensive manufacturing that is carried out in these "evil" countries. The cost of manufacturing here for those types of products will never be priced even remotely competitively on an international scale. But there are tons of things that America can do extremely well like research, agriculture, and high tech manufacturing. But instead of building an economy geared toward our strengths, those are being gutted in favor of trying to please people that don't understand why cheap consumer products aren't manufactured here.
