You are touching upon a real problem here. America hasn't had excess labor for decades now, and so there are no systems in place to rapidly mobilize it. Governments in countries like China and India can scale from zero to millions of temporary employees for any project or effort in a matter of days. Even if San Francisco wants to pay people to stand at every intersection of the city and conduct tests, it will be months before they can even fill out the employment forms and finalize the logistics.