This Slate article explains why toys "face" a lower tax than dolls. So Transformer are action figures that are taxed lower than a Barbie. Given that the elasticity for toys and dolls are greater than 1, it would seem to be a frivolous tax. I think Logistics is the reason.
I know that less than $1 USD is needed to make a Barbie that sells for $9.99 in the States so the import duty is nothing. So why have the duty? Because shipping Barbies takes up valuable space for other more important goods.
If I ship a million dollars to the States, I can't ship food. The tax represents the opportunity cost. (Hat Tip goes to Gene Hayward who makes a difference with his teaching.)