The biggest bank is a phone operator and people can send each other money over the phone and from what I understand this is very common. Also interestingly most phones aren't smart phones. It's mostly analog. Banks have a serious incentive to create and encourage cashless societies -- because they're limited by the liquidity ratio.
People there are more skeptical of hard cash there while here it's nearly on par with Gold in terms of confidence.
I don't think I've to explain offering an API allows third party engagement and endorsement and an opportunity for others to grow their service. Yes there are security concerns but these can be all secured from backend.