(EDIT: To everyone saying this is a bad idea: yes I agree, and that's unrelated to my question. Before reading my subsequent paragraph, note this sentence can be interpreted two different ways. I thought it meant "automatically" as in "without needing to manually copy-paste" (to avoid phishing), but it seems maybe the intention was "without prompting the user"? The second one seems like bad advice and not what I was asking about regardless - I'm asking about the anti-phishing fill where the program enters the text, NOT about unprompted filling, which I already agree is a bad idea.)
It's not this simple in reality is it? Surely it's not just me whose password manager often has to prompt to fill in a legit website it can't recognize, because the domain or URL isn't the same as what it has stored in its database? Are non-technically-inclined folks expected to be able to follow this advice in practice?