It would also be completely unrealistic as millions of Brazilians would just go to the US and stay there. Reciprocity doesn't work between countries with significantly different wealth and standard of living.
I've been on the receiving end of US visa process. They require you to demonstrate that you have substantial ties to your country that would make it more likely that you'll eventually leave the US. Income, real estate or other assets, children/wife staying, that kind of thing. That's not a guarantee you'll return, of course, it just makes it more likely.