Its surprising, ineffective and wasteful, to have 50 different apps made with different criteria, etc. instead of a single one by the federal government, I think of city clusters that stretch two or more states, like the Boston-Washington Northeast corridor... its not like people don't commute from NJ to NY, from Delaware to DC, also... domestic air travel... does different apps using the exposure API by Apple/Google communicate between them?
If you really think about it, from a scientific stand point, there should be one global app for this... maybe developed and run by the UN and promoted by national governments... of course, you get politics in the mix and we have what we have now... the US out of the WHO, the Chinese withholding data, some national entities lying and denying the pandemic, etc...
Yes to a number of your points. I think the central reasoning arises out of our (the US's) long history with concepts of federalism. I've observed that many people--including people who were raised abroad but also people raised in major population centers in the US--don't adequately appreciate how rooted notions of the highly layered patchwork of shared power and areas of authority are. And the lines between city, county, state, regional, and federal authority are always changing by legislation or judicial degree. Efficiency has not been the overriding concern for most of our history with regard to healthcare . . . anyone remember the number and breadth of fights over "Obamacare"? . . . or any number of other areas, actually. We are about to be hit over the head in three months with considerations surrounding the proper role of people appointed to the Electoral College, especially in a likely close presidential election. The Supreme Court of the US just had to issue a ruling dealing with this subject, as they were convinced they needed to preempt some of the possibilities.
Anyway, there is next-to-zero chance that local leaders in Mobile will see COVID-related things the same way was local leaders in Manhattan. Personally, I applaud VDH's approach to put privacy and standardization on Google's and Apple's platforms at the forefront. I can easily count five other examples in the news where local or national leaders somewhere in the US or Europe have decided to go a different way because they believe they know their peoples' needs better than Google and Apple. Several of those are, apparently, still working on getting their apps out, though. Most goverments don't have deep benches Android and iOS developers, it seems.