It's utter incompetence and laziness. But when you vote in lazy incompetence, then that's what you get.
There's a list of real tariffs for various countries here https://x.com/ianbremmer/status/1908609257756336239
The circular situation seems not so common but countries like Camboidia don't import much from the US because the people there don't have much money, so the Trump formula makes their 'effective rate' 97% whereas their actual tariffs are 7.9%. The net effect is to hammer the poorest countries.
Ironically the Cambodians don't have much money to buy US stuff because of terrible governments that got in partly as a result of the US destabilizing things by bombing the country. They don't seem to have much luck with the US.
Laos, Cambodia, Vietnam, Korea, El Salvador, chile, Colombia, Iran and on and on.
Now it seems there is just one country benefiting from their relationship to the States…