Just basing this on ads (so I don’t suggest taking it at face value). The primary selling point of mobile banks is that they can offer higher interest rates than traditional banks just because the savings bought on by the lack of brick-and-mortar infrastructure are passed on to their clients. The mere handling of loads of physical cash around is already a costly endeavor involving armored vans, endless security measures, vaults and auditors.
Mobile banks also used to have an edge because they had optimized cashless payment channels whereas in traditional banks, you had to fill out a form and wait for 1-2 banking days just to register a merchant. Nowadays, the old banks are catching up though.