A small number of other countries with well organized governments, good epidemic response teams, manageably small populations and strong IT infrastructure. Now

A small number of other countries with well organized governments, good epidemic response teams, manageably small populations and strong IT infrastructure. Now imagine all of this being done effectively in a country with several hundred million people, many of them extremely (and not entirely unjustifiably) opposed to privacy invasions and mistrustful of their government in many ways. That's the U.S I speak of in case it's not obvious. Now go a bit further and imagine this same mass testing and contact tracing procedure in the majority percentage of the wider world that actively lacks good government, good administration, has terrible infrastructure (clinical especially but of any kind in general) and is largely poor. It doesn't require an epidemiology degree to see the difficulties. I can't even easily imagine the mechanics of effective mass testing and contact tracing in places like India, Latin America or large parts of Africa, with hundreds of millions of barely documented residents living lives steeped in informality.(I live in Latin America and have actually seen how poorly government in my country manages even basic testing) It's good that testing and contact tracing are attempted where possible and continued wherever they work, but let's be realistic about the fact that a majority of the world outside these places will drive the dynamics of the virus with a social weight well beyond that of the minority population of regions where the above work, and in that same majority part of the world, mass testing and contact tracing have very little chance of effectively being applied. In essence, remember that most people don't live in the well-structured bubbles of small European and Asian states with relatively efficient, modern administrations.