The UK tests a lot in order to predict hospital demand, but there are so many infections that only 30% to 50% are ever detected; the origin of most infections go unaccounted for.
In Australia and China, a single positive test triggers immediate local lockdown and local mass testing, until every case is accounted for, further trace-and-test turning up 100% negatives. This takes around a week and then lockdown is lifted. As soon as infection is detected, people need to be kept still to stop it spreading while its extent is being traced. The net result is that citizens spend on average about one hundredth of the time under lockdown as Europeans.