So this bank's ATMs...
... come with a guarantee of proof against quakes and tsunamis too?
If not, then that "this secures against loss of passbook" argument doesn't hold (back) much water, now does it?
But I guess it's a nice incentive to explore faking vein patterns. Or maybe it's easier to just try to somehow obtain or guess the birthdates and PINs of the customers, and with that "authenticating" a handy substitute limb. Purely for academic purposes, of course.