Because people don't give a shit and are just moving around without masks and not social distancing when they are tested positive.
I have seen people purposefully coughing on handles on the trains and in shops, that people are going to touch, it's like they have human rabies or something and are acting horribly and instinctively without and reason or logic.
The UK people are degenerate, postering idiots that deserve everything they get.
Stay indoors and give the NHS a chance you tools!