The best instant payment system is cash. It allows the merchant to skip the taxes too. Unbeatable.

Cash is a hassle. It requires everyone to have change. You need to count the money, the cashier needs to count the money and store it. The line behind you gets longer. The end of day close-out process is longer.

Brazilians also generally don't like to walk with cash in their pockets. Only politicians usually do it, but in their underpants.

The pros is that cash is analog, no battery, internet connection or digital system needed to process it.

Cash is king - but security is an issue unless you are dealing with small amounts.

Also allows the employees to skip paying the business too.