Covid Virus to Get One Week Notice?

The UK government is finalising its traffic light system for non-essential (i.e. holiday) travel (https://www.theguardian.com/politics/2021/may/01/travellers-to-get-one-week-notice-of-overseas-rule-easing-as-ministers-play-it-safe). The 'green', 'amber' and 'red' lists will apparently be based on the:- 1. Prevalence of variants of concern; 2. Its access to reliable scientific data and genomic sequencing; 3. Rate of infection and 4. Percentage of the population vaccinated. All of these criteria will not be easy to assess accurately. Visits to countries on the 'green' list will require no quarantining on return. Apparently, 'only' one-week's notice, will be given for changes in a country's designation. This has, predictably, upset people running airlines and travel companies. The trouble is that time is 'perceived' differently by humans and viruses. Consider a human trying to swat a fly. The reactions of the fly are so much faster, making the swat difficult (or requiring equipment). One week sounds awfully short for people trying to plan a foreign holiday. A virus, however, can replicate, after infecting a host, in about 3 minutes! The rush for foreign holidays is understandable but, probably, ill-conceived.