Earlier quoted context omitted.
Brazilians can already do inter-bank money transfers using their bank accounts apps cheaply. Pix is an improvement over those systems (shorter processing times - as in seconds instead of minutes) and checks are almost nonexistent.
I wouldn't say cheaply... Unless you have a digital-only account or has a high-class account (like VanGogh,Personalitté, etc) it's cost almost 9 BRL for a inter-bank transfer.
Compare with https://answers.usbank.com/answers/s/article/How-much-does-a... (spoiler alert: 10x more - for both senders and receivers)
Whatsapp transfers would be ~ 5% of the cost which would make it more expensive for anything over 200BRL
Meanwhile inside the SEPA Area (EU), National and International payments have the same cost (which is usually 0)