A good question! I certainly can state that mobile banking is safer from a mobile device than from an internet browser because the latter can be compromised because it’s more open to the internet and issues that you install anti-malware software to protect you.
I would judge that the fact that as all software downloaded onto these devices go through a “shop” maintained and supported by the hardware vendor that they have done checks on the software and the supplier before releasing it through the shop. That’s a very powerful first step and is why I’m a strong supporter of these “shops” and would be distressed if some alternative means of downloading software onto a mobile device was allowed.
However, nothing protects you against yourself and that’s where the hints and tips in the third part of my “Protect yourself online” talk come into play.