Perhaps the actual cost cannot so easily be summarily dismissed.
Well, I reckon it can. Within the overall cost of the pandemic, the cost was
tiny.
Minute. Think back to when it was brought in - the panic and unknown descending on us - "Oh, we are going to put this App thing out to tender; a review board will look at it, then we'll leave time for public consultation and expert opinions, etc etc etc ..." I'm not one to waste taxpayer's hard earned on anything, but given the circumstances & urgency at the time, I reckon its not the worst expense we are going to have borne, by a long shot.
25% to 50% would be a total fail in any exam I ever did. So for half of the phones, it would work somewhere between a quarter and half of the time.
I agree re the 255 to 50% fail - if it was an absolute thing, like an exam. But the app was never designed to stand-alone, but only as an adjunct to conventional tracing. Half the phones (iOS),
if locked and contacting other locked phones would fail under your definition. In other situations, they don't, according to the table above. Not perfect, sure, but not as direly bad as you seem to make out. Again, it was never designed to be a complete answer, just an adjunct tool.
____________
Hey, I don't have any royalty stream on the damn thing - but judge it for what it is (better than how it started), the circumstances at the time it was developed and what it was actually designed to do, not as if it was flogged as a cure for the whole damn pandemic.