[inimino]

If it is built in the US, regulating the sale would be redundant, as manufacture would already be illegal, and more ethically made products don't look any different.

If you want, say, textile workers to have humane working conditions, you regulate the textile manufacturing industry, and you want enforcement officers in the garment district, not the retail district.

[parhurs]

>If it is built in the US, regulating the sale would be redundant Obvious, but the question was about things NOT built in the US and actually illegal to build in the US. Why are they not illegal to sell there?

[inimino]

First, as Americans seem so easily to forget, other countries actually have their own governments. Why should the US government try to enforce US labor laws inside the borders of other countries?

Second, trade agreements exist and are a more effective way to do what you want.

Third, it is impossible to tell how a product was made by looking at it. How would you enforce a law that makes a product illegal based on something invisible?