Paying for a bus fare using USSD is delusional, to be honest those guys want to maximise on cash transactions understandably so, I can understand increaseing your wallet balance for things like change which is practical, but paying for bus fare when the operators may choose to hike their fares during peak hours would not work out to their advantage what so ever.
I've mentioned RFID and NFC in previous posts and that truly would be innovation. Ecocash works just not everywhere and not for everything.