> Cochrane Review

Our confidence in these results is generally low to moderate for the subjective outcomes related to respiratory illness, but moderate for the more precisely defined laboratory‐confirmed respiratory virus infection, related to masks and N95/P2 respirators. The results might change when further evidence becomes available. Relatively low numbers of people followed the guidance about wearing masks or about hand hygiene, which may have affected the results of the studies.

If all of us lived in a controlled environment with less variables and were consistent with hygiene policies sure but let me tell you that doesn't even happen in a hospital unless you're in a isolated environment such as during surgery. And also it helps that in hospitals the air change and HVAC requirements are much stricter.