Amazon provided me extra discount on top of a discounted price.

But only for selected products. It's easier and more manageable than my bank credit card rewards.

Also many services like doctors, vets, etc are much easier to pay.

The only upside of CCs are rewards and cashbacks, but if they add too much rules, and exceptions for it, pix becomes the clear winner for the transparency on my expenses.

So even for people on middle to upper middle class it can have more benefits.

I can say for a Russian system which looks similar to me: banks do not charge additional fee (acquiring fee), so it's beneficial for shops and small businesses. It works instantaneously, you don't have to carry your card with you (people now always have phones with them but sometimes forget wallets or cards, also phones are locked and cards can't be locked).

Small business doesn't have to pay for anything but a piece of paper with QR code printed on it.

There is little question that, if this becomes the dominant way to settle payments, prevailing prices will decline by an amount proportional to the previous transaction costs. That is obviously a significant benefit to the consumer.

No fees for merchants and no external global entity that can see everything you purchased.