Cashback is just giving part of the profit margin of the fees charged on the transactions to the customer. I would rather that profit margin gets split between the customer (lower prices) and merchant. Also, didn't the EU eliminate cashbacks by precisely price capping transaction fees?

I've seen merchants giving a discount for payment with Pix. And a few stores refuse credit cards and only accept debit and Pix (and cash?).

Also, isn't the main competitor to CC the debit card? And now in some countries instant payments? Is debit that rare in the US?

Although to be honest I'm not 100% sure if it isn't some tax evasion thing.