It is 500,000 for doing nothing, 250,000 for mitigation and trying to keep it under 20,000 for suppress. Measures to keep it under 20k are now the aim it seems.
Do you not think it is ok for the whole population to be restricted to try and keep deaths under 20,000? If they didn't then we'd be back to the 250k or 500k figure.
None of these measures are used for seasonal flu because you don't get 500k deaths in the UK, that is why they are needed for this!