Indeed, we only offer credit cards payments to simplify and secure things.
Payment by direct debit is binding and obliges us to keep bank details in secure locations. Risk we didn't want to take.
Paypal payments could be possible, however the commissions charged by paypal and the risk of password loss / theft were prohibitive for us.
Other paperless solutions are possible but unknown in France.
Our payment module accepts almost all credit cards in the world, including American Express.
So we decided to offer an unique and simple solution with payment by CB for all.