We are not a police state. People will not be held at home under armed guard. Those who need care won’t just be abandoned because they are self isolating. Those who would rather take their chances will almost certainly be permitted to do so.
Those who are over 70 and/or have certain pre existing conditions are more likely to become critically ill and die as a result of this virus. If you want to reduce death rates you reduce the number of people in highest risk groups who get the virus. In the same way that they vaccinate high risk groups from seasonal flu (I know this is different to the flu, it’s just an example).
There is no vaccine yet, so we stop those most vulnerable to the virus from contracting it as best we can. Within that group of people there will be those who cannot isolate entirely or who chose not to. The fact is if say, 50% did isolate it would make a big difference to the overall death rates I suspect.
If they were saying children under 5 were most at risk I wouldn’t be leaving the house with my DC because I would want them to stay protected.
There will need to be other measures too. Chris Whitty did set all this out weeks ago. None of this is new.