I kind of agree with what you’re saying but all security emphasis cannot be put onto Monzo. They could have it like a vault and it can still be vulnerable due customer habits / configuration.
In the example above you’d configure your phone to lock after x seconds/minutes so this has nothing to do with the Monzo app.
Likewise If it gets hacked this will be because you lost the phone, had a poor password or revealed your details publically. Monzo again cannot be responsible for this.