I would believe that Amex and Banks have their own chreking procedures and they are each different.
My guestimate is that Amex are very reliant on using their own internal checks, and that once you have had an Amex that future approvals are generally pretty painless. So I rate it as one of the easiest to get new cards for.
I have been churning cards for bonnii pretty solidly for well over a decade (It has come and gone a bit as in some years sign-on bonnii have not always been as lucrative or as valuable as they have been the last couple of years) and of all the organisations that I have applied to the ANZ have checked more often, and more rigorously than the others. Indeed with ANZ it pays not include things like your investment income as they have sometimes asked for ridiculous things like wanting to see proof of all dividend earnings...and when you have thirty odd shareholdings that is simply not going to happen. So while I have always gained any ANZ card I have applied for, they have tended to be more effort to gain.
