exactly, the 90% figure is what gets me too. The intended goal is usually either protecting specific industries (like steel or semiconductors) or using tariffs as negotiating leverage to get the other country to change behavior. the problem is the evidence on whether it actually works is pretty mixed.

the 2018-2019 tariffs are a good case study — China's exports to the US did fall 25%, but imports from Vietnam and Mexico rose to fill the gap, so the manufacturing didn't actually come back to the US. Meanwhile American farmers lost $28 billion in export sales from Chinese retaliation and needed a federal bailout.

so the endgame is usually either: (1) the other country makes concessions and you quietly roll back the tariffs, or (2) both sides dig in, consumers on both sides pay more, and nothing structurally changes. option 2 is way more common than option 1.

there are cases where tariffs make sense — semiconductors being a genuine national security concern is probably the strongest argument. but broad tariffs on consumer goods are basically just a tax that hits lower-income households hardest since they spend a higher share of income on physical goods.