It's not like the latters are made in brazil. Does brazil have special punitive tax rates towards US based companies?
Or is it just that the local equivalent of VAT goes up fast with the phone price?
Right in the middle of the Amazon region there is a development zone where the majority of the electronics are made, in the country, by multinationals. It is called a Zona Franca.
When built in the country the import taxes, which represent the majority of the cost for imports such as electronics, these taxes are removed and make the good much cheaper.
It is the same with Xbox and PS4 in Brazil. An Xbox is 4 times cheaper than a PS4. If Brazil would be against USA or it's companies then it would be the reverse.
Hope I helped.
ps. Many people in country complain about the taxes but forget that when companies move their industries to Brazil, jobs, money and know-how stay there too improving the competitiveness. Sadly the vast majority of the population will look the price tag and complain without knowing the implications behind.
Actually, they are. There are Nokia, Samsung and LG factories in Brazil, as well as a tax-incentive zone in the Amazon region.
There were, once, local manufacture of Apple equipment (I have a Powermac 4400 from that time), but it didn't survive the takeover by NeXT.