The problem is all this is closing the fence after the horse has already bolted. The average person arriving into the united states is less likely to have covid than a resident. Currently 2.7% of the US population is infected with covid19, compared to 2.4% of people in the UK, 0.9% in Italy, 0.2% in Canada, and ~0% in Australia, NZ, Singapore, India, China, etc.
Almost all new infections in the US come from domestic transmission.