NEED TO KNOW
The money thing in Argentina is complicated. The official exchange rate is about 50% worse than the street rate, aka "Blue Dollar Rate". You can check the daily BDR at https://bluedollar.net/
Avoid changing money in a bank.
Avoid withdrawing cash in an ATM.
As of January of 2023, foreigners using a foreign credit card will enjoy an exchange rate closer to the BDR (about 12% less). That's much much better than the official exchange rate.
[Updated on March 7, 2023] When using your credit card, usually there is no need to show your ID document. The only exception is a grocery store of Coto in BA.
BEFORE THE TRIP
Before you start your journey, make sure that your credit card has no foreign fee or very low foreign fee when you make a purchase overseas.
Sign up with Western Union of your country (e.g. USA, or Canada). Link it to your bank account, or a debit card. Install the app on your phone.
ARRIVING AT EZE AIRPORT
Buying a SIM card:
At the exit hall, take the lift to the second floor. There are a few stores there. There is an office of Personal Flow, a mobile service provider. You can buy their SIM card at the cost of ARS 1000. It's 5GB of data, 30 minutes of international calls, 100 minutes of domestic calls, for 30 days. My credit card bill shows that the transaction cost CAD $4.28.
Going to the city:
The cheapest available way is to use UBER. The cost of my ride is ARS 4,880. In CAD it's $20.10
Every rider has to use a public transportation card called SUBE. Can be purchased in a subway station at the cost of ARS 490. You need to recharge with some ARS. Usually a ride is less than ARS 100.
The best way is to do a Western Union "cash pickup". You start the transaction on your app. After it's completed, you get a tracking number. Go to a local Western Union office with your passport and the tracking number, you will be able to get ARS cash. The exchange rate is very similar to the blue dollar rate. Sometimes it can be even better.