There are a few things here - 1) You don't have to remember that you need to pay. You pay instantly and be done with it. 2) Jenny may be someone you don't often see. 3) You're away but want to pool in for a gift or celebration back in town.

Thank you.

I don't see the point here. I mean, I could write Jenny a telegram if I wanted to tell her something. Am I missing something?

Sending the SMS is instant, waiting until next time isn't.

And what does instant payment bring ? To me, it looks like a solution looking for a problem.

PayPal did pretty well with the idea.

PayPal is about secure payment, it doesn't need to be instant.