As you say, different countries operate differently, even within the EU. I have both a debit card and a credit card, both of which are free. I am in the UK. The debit card is useful when I need to draw cash, and the credit card covers most other transactions, including online ones. Life would be impossible in the UK without one or the other, but both are better.
Nowadays I very rarely use cash. Everything is paid for by card, even small transactions and bus tickets. We are truly a cashless society now, and it works. But in places like Austria, they cling to cash. God knows why, dealing with cash costs a lot of money.
But getting back to the point, I believe Haiku needs to have a European bank account to faciltate receiving cash in Europe.