If I cannot see somebody's full face when they knock at my door, even on a legitimate errand such as reading the meter, they would not gain admission. Similarly I would not admit somebody wearing a hoodie or a baraclava. I simply want to recognise somebody and see who I am dealing with.
If they refused me that courtesy, I would not admit them. It's simply a case of wanting to feel safe in my dealings with that person. If they won't provide an environment in which that can happen, I won't do business.