Looking at AWS site it explains that PIS/COFINS and ISS are charged, excerpt below:
"AWS SBL can issue an NFS-e to a Bra zilian customer only after receiving a valid Tax Registration Number ("TRN") (i.e., CPF/CNPJ). The relevant taxes applicable to AWS cloud services offered locally are the following: PIS and COFINS (9.25%, combined rate) and ISS (2.9%, charged by São Paulo municipality)."
https://aws.amazon.com/tax-help/Brazil/
This is below 15% which many countries do tax for cloud services.
I'm not saying that Brazilian taxes are really high, they are for hardware imports, but the taxes into the service itself does seem "fair".