The electronic voting system is auditable though:

https://portal.tcu.gov.br/en_us/imprensa/news/tcu-audits-bra...

There are many valid criticisms against this system. It not being opensource, it's audit process being very restrictive etc... There is a nice presentation following a conclusion of a vulnerability test that highlight many of the issues: https://youtu.be/4MgsGdbtf6o

But this impossibility you claim is just nonsensical.