The thing is, direct conversions do not really work. I don't think they operate much in Brazil, but if they did, the salaries would be adjusted to the Brazillian reality (minimum wage, average person income, purchasing power, etc), so in reality, it would be much less than 28 grand USD.
The more real conversion is to use a purchasing power index, such as the big-mac index. Using the 2018 data for the big-mac index, that would probably equate to mostly 30.000,00 BRL, which is 2500 BRL/month, which is above Brazil's minimum wage, but it's still a very basic salary, probably comparable to earning 2200,00 USD in the US.
The point is, we don't know how the data was presented by Amazon. I'd expect that the wages reported would be in USD to show how much it actually costs to the company in the United States, and not some weird index.
If they pay, say, R$ 30,000.00/year, I doubt they'd report anything other than the direct conversion to USD.
I've watched a series of lectures on the subject by Harvey Mudd college, on youtube [1]. It helped me a lot, tho, I'd have to say these are introductory level, not really a deep dive, but more useful as an introduction.
[Edit]: Styling and phrasing