> Evidence to date outside Asia is, zero flattening
That's not true.
"new daily deaths" are fairly flat in Italy over the last week, not doubling geometrically at all.
https://www.worldometers.info/coronavirus/country/italy/
If the lockdown is working in other countries, then a similar state will be reached 3 weeks afterwards.
Daily new cases is down in Italy since peak on 21 March - that's a leading metric compared to deaths, although it is less precise because it can be swayed by changes in testing.