Just read about another mobile-only credit card that is currently crowd-funding.
A bit of discussion here as well - The big boss came on and answered some questions.
TL;DR - It’s aimed at people building their credit history.
I just don’t get why they want to waste time of a pre-pay card and then 6 months later launch a full card. I understand a company moving from pre-pay to post-pay its a logical progression, but to purposely spend all that time and money seems a complete waste. Monzo did something similar, Starling didn’t. Monzo might have the customer numbers, but Starling offers a very different product (I know the current account is similar) because its didn’t have to work on a pre-pay product.