We're about giving people a system to control their digital identities and to use it as and when they need to prove their identity and create trust online. It works by the miiCard user linking to an online bank account to get that level of validation of identity (your bank has done this by sighting various forms of photo identification; passport, driver's license, and sometimes utility bills). Once your miiCard is validated you can tie in your other online accounts such as Ebay, PayPal, LinkedIn etc. At every stage you are in control with what amount of your information you share with others.
So I guess you have to trust your bank. We know it won't be for everyone, but there is a need for creating trust online and that's what we're aiming to do for those who see the value in it.