Simply. When I log in to Amex there is an option to 'trust' web browser meaning Amex will not ask to enter two-factor auth code for at least a few weeks when using the same device. Cookies are used for this. But Simplifi doesn't benefit from it and each time I log in I need to request and enter Amex code. With time more banks add two-factor and logging in to Simplify will be a pain. Why don't you act like a browses saving cookies and becoming 'trusted' device?