The main reason companies like Yolt, MoneyDashboard and even Android and Apple Pay do what they do for free, it’s that they gather your data anonymised and sell spending trends and general purchasing data insights with their clients.
I’m a strong supporter of the use of my anonymised data in exchange for ‘free’ services type agreement.
Having said that, Monzo only have to gain from integrating with the main stream financial services that provide open banking such as Amex. After all, if Monzo is ever to cross that profitability line, market spending data insights could be an important part of revenue.
Would also help Monzo to get a better credit score information for their users by gathering this data in order to provide a more precise marketplace service based on credit score without having to use legacy not so precise systems such as Experian or similar.