A tucked-away foot note on the CDC website reveals that they admit themselves that face masks don't have evidence that they protect people. They say there may be, may, might, perhaps, be a reduction of spreading the infection if the sick person wears a face mask. There is less information about any protection for contact with someone with COVID-19.
https://www.cdc.gov/coronavirus/2019-ncov/php/public-health-recommendations.html
While research indicates masks may help those who are infected from spreading the infection, there is less information regarding whether masks offer any protection for a contact exposed to a symptomatic or asymptomatic patient. Therefore, the determination of close contact should be made irrespective of whether the person with COVID-19 or the contact was wearing a mask.
If there was real evidence to prove masks were effective for people who are sick to prevent the virus from spreading, they wouldn't say "may". The evidence already exists for how viruses like influenza still get through cloth masks and make no significant difference in spreading the illness. It might stop some of the virus, maybe. But it still gets out and makes no significant difference in previous studies.
I think if you are sick with any cold or flu like illness, it's a decent thing to do to cover your mouth when you cough, or your nose when you sneeze. Rather than letting it spray more freely. Masks seem a bit better to contain the droplets, but the virus is smaller than the pores of the mask.
The evidence for people who wear masks thinking they are protected from others who are sick doesn't exist. The mask manufacturers even put on the boxes that their mask won't protect you from the coronavirus. All the randomized trials in the past show no significant difference between wearing a mask and not for the virus to spread.
Are we going to get randomized trials now to prove they do or don't work? No. Fauci says that's unethical to let people not wear masks. There would be thousands of people willing to take part in that study and not wear masks. But then the excuse is to sustain the lie anyways, that if they get sick then they are spreading the virus and that's unethical.
Either way, no trials will be done to prove if masks work or not against coronavirus. The real reason, in my opinion, is that they don't want the results. They already know based on previous studies that the masks won't prove useful. It's better to just keep the lie going and not require any proof. People are buying the deception so far, and will continue to.