//If no tests are done and no one knows they have got it, they will super spread it and more people will get it, and more will become ill.
Pretending it doesn’t exist by not looking for it solves nothing. Ignorance is not an excuse.//
//It’s naturally the case however it’s also likely the case that more infection means more tests. No one claims that these figures are the be all and end all.//
You are both correct – and both missing the point.
The point is not how many tests should be done (though I would argue that only people displaying symptoms need be tested, but that’s a different question). The number of tests undertaken clearly has a major influence on the number of positives found. Although it has increased in the past week or so, the percentage of positives has not varied greatly throughout. But the number of positives has varied enormously. Whilst random testing is taking place (where round about 95% of those tests prove negative) it is vital to know how many tests are taken to account for the positive results. It is important to know the absolute number of cases because, as PP mentioned, the medical facilities needed to treat Covid patients are finite. But to simply state "new cases doubled in the last two days" without knowing how many tests were undertaken is meaningless.