You're talking about close contact between patient and nurse, and when the patient has an infectious illness, a mask can held reduce the spread. In most other cases, they are not useful. And in all cases, they come with risks, and most people do not use them correctly, causing a false sense of security that ends up spreading illness.
It is not "unconscious" to be aware of the actual scientific data and clinical experience, then take action based on it. Our practice should be guided by logic, not superstition and dogma.