Yeah, I understand.
The main problem may be Brazilians who don't actualy know the laws or that are too lazy to file a tax review. In some states purchases up to $100 dollars are tax free, in others, up to $50 dollars.
Amazon started charging duty fees on the Billing page, so you already pay about 60% duty tax in advance, even if it's under $50 or $100, and Brazil drifts away from the international market step by step.
For mail forwarding services to Brazil, the US has better rates, but still, too high. If the goods are not that expensive, like a Pi Zero, i'd pay 5 Bucks for the Pi, and about 20 Bucks for shipping + handling