Pix is not an app but a platform (like INTERAC in Canada). It works with most banks and most people with bank account now have it.
Not only that, it is not just a QR app. You can send money to any key, that can be:
- An email
- CPF (unique SIN / SSN number that in Brazil is not considered secret)
- Telephone number
- Randomly generated key
The transactions are also, for the most part, instantaneous (think 1-2 seconds) and irreversible (as far as I know).
Even if you only have in your phone apps for banks without a Pix key, it is trivial and fast to create one. Unfortunately the only way out of this is to never have on your phone a bank app (and they can even force you to download one on the spot if you are actually kidnapped).
Also, from someone who was carjacked in the past in Brazil: this has always happened here. I think it is simply the delivery method that is changing. Unfortunately, ban those apps and the bad guys will just go back to randomly kidnapping / carjacking people on the streets of rich neighbourhoods like they did in the past.