Aamericans tend to over engineer, an approach which in many cases can be very desirable, but in this case would result in 1 inch thick of the heaviest rubber, with a tread, with a leather covering for entire foot, up to over the ankle, and the whole thing held together with shoelaces.
Without De minimis you would need a customs structure say, a hundred times larger, or more, I dont have the figures, but it’d be ridiculous.
Also, it would make people buy from the big importers, who would have the capacity to process many shipping containers in one go, and these would have it easier to impose the prices they want, since consumers woulnd be able to source from overseas. De minimis makes a lot of sense.