I think it’s not remotely practicable to implement the sort of nuanced approach you suggested whereby the legality of travel or requirement to quarantine is based on a matrix analysis of who, how many, where, what activities, etc. You could certainly design such a system, but communicating it and enforcing it would be impossible. Look at the difficulties evident in the pages and pages of threads on FT when dealing, for the most part, with only one variable (where).