First, only a very small proportion of the masks 3M makes are made in the US. The vast majority are made in China. Trump asked 3M to prioritize their US production for US use instead of sending US production elsewhere and depending on masks from China only coming to the US. I don't see anything wrong with that. New York City alone has more cases of COVID-19 than the whole of Canada. Seems reasonable to prioritize getting the masks made in Minnesota there first, rather than waiting on masks to come from China.
The other point is that if there are millions and millions of undocumented cases, that would be a very good thing. Think about it. If, instead of there being 300,000 cases, there were 2,000,000 cases, you have dramatically increased the denominator for the case fatality rate. That drops the US rate from 2.5% to 0.35%, making this a very different characterization of COVID-19 than initially believed. Additionally, it would mean that there are a lot more people immune to the disease than currently believed.
Third, now that private laboratory testing has taken over the majority of testing, results are back in only a couple of days in our area. In New York City, the patients who were "accidentally" transferred from the Javits Center to the hospital ship (which was supposed to be only for non-COVID-19 trauma cases) had their tests come back positive the morning after they were taken. And once the new instant test kit Abbott developed gets distributed widely, there will be "instant" in-office testing available just like there is for influenza and strep and other things.
As far as how many people are getting tested, in my state, Missouri, there have been 2291 people tested positive, out of 24,727 people tested. That's only one out of more than ten people tested who have the virus. The case fatality rate in Missouri currently stands at 1.0% If you estimate that 30%-50% of those infected are asymptomatic and therefore would not have presented for testing (these numbers come from actual research in countries that did widespread population testing and from the cruise ship petri dish) then the case fatality rate would drop to as little as 0.5%.
Finally, with regard to mask use, the purpose of masks worn by the general public is NOT to prevent the wearer from contracting the virus. It is to prevent asymptomatic virus shedders (those who either have an asymptomatic infection or are in the prodrome phase of the illness before they exhibit symptoms) from infecting others as they go about. It works with normal cloth or paper or synthetic surgical-type masks because it keeps droplets and spray coming out of the nose and mouth and getting on others or objects. Respirators used by health personnel are an attempt to filter virus particles out of inspired air. To do so, they must seal against the face and must have sufficiently small filtration size. N95 masks are supposed to block passage of 95% of particles 0.3 microns in size. 0.3 microns is 300 nanometers. The SARS CoV-2 virion is 50-200 nanometers in diameter. Conclude what you will about that.