Yeah we would need to do daily testing too. The main problem is that (a) it takes 3-5 days for the infection to become detectable and (b) it takes 1-5 days to get your test results back. So for 4-10 days you are contagious and don’t know it. Instant testing like this that works before symptoms means you could detect the infection soon as it takes hold, significantly reducing the spread rate. If our traditional testing was all rapid we would be a lot better off. Well that, and leadership that isn’t solely concerned with its own reelection in a pointless bid for staying out of prison. Both would be good.
But we could all cough into our phones every day.
What you describe is what South Korea has done a couple of times now with more traditional testing, it certainly works if you actually do it.