The biggest entry barrier for this service is the cost of the vending machine starting at around $160 for the basic one and around $250 for the multi-feature variation. They also have an online portal to generate codes but it requires a very good and stable Internet connection to avoid irritating clients. However reliable mobile Internet in Zimbabwe is either very expensive to use to run an airtime business or is not widely available (with the exception of Cafes with 24/7 wired Internet Access).
A business suggestion for free for Easi: finance the Vending Hardware and watch as every corner street airtime vendor adopts your Genius devices.