Only a small fraction of the world has been infected. It’s a new disease. Variables will change.
R0s for interventions are guesses, in some cases informed by data. There is no historical precedent for what is going on right now to draw from.
The default R0 used in this model is an average. The model does not adjust for the population density, culturally-determined interaction frequency and closeness, humidity, temperature, etc in calculating R0.
This is not a node-based analysis, and thus assumes everyone spreads the disease at the same rate. In practice, there are some folks who are “super-spreaders,” and others who are almost isolated. Interventions should be targeted primarily at those most likely to spread the disease.