Just to add - there is a significant difference for merchants...

Just to add - there is a significant difference for merchants between the systems.

The apps which Retireby describes are treated as "card not present" (CNP) which means that the liability for the transaction lies with the merchant. It the customer decides to dispute the transaction then it is very difficult to prove the customer bought it (as you don't have the mag swipe or chip data).

Additionally, on a per transaction basis, the cost is a lot less. CNP have a higher merchant service fee. If you can do EFTPOS (with PIN) it is super cheap, $.20-$0.50.