It's not that simple, because 1 person who has multiple contacts, visits many places etc. will have a far bigger impact than 10 people who all get through customs and go straight home, work from home and have little contact with anyone. This is where track and trace nailed it in South Korea, no...
I suspect you've been so succinct knowing you'll stir up a bit of controversy simply leaving it there.
Leading up to 23 March Britain appeared to be following Sweden's approach of a light touch, no scientific evidence that lock down works, socially distance and do all the things you can, but...