From what I understand, the desire for instantaneous transactions is has an inverse relation with how much money you have. Poorer countries are generally way, way ahead in mobile banking, because in a rich country you are supposed to keep around a month's salary in all your accounts, making transfers less urgent.
The way I understand it, it's a coordination issue - the bigger a market is, the longer it takes for a big change to be adopted by everyone.
Plausible stories are easy to make up. Lots of countries - probably most - with higher GDP per capita than the US have lower latency banking. The US has a large proportion of people who are worse off than the equivalents in many poorer countries, too.
Your perspective describes the underlying issue much clearly than those who talk about "leapfrogging".
The newer platforms (like mobile banking) were adopted in those (poorer) markets because they were cheaper to deploy relative to the technology that preceeded them, and perhaps more importantly, they had less inertia to overcome (against entrenched interests).
That, and how much existing infrastructure there is.
Many places leapfrogged directly to mobile phones (featurephones mostly) because there were little to no power and/or landline wiring present (and attempts at getting such infrastructure in place got disrupted by people stealing the wiring and selling it as scrap copper).
