At the risk of repeating myself: highway=pedestrian is an appropriate tagging for roads on which vehicles are never permitted. This is very clear from the wiki. Our evolved norms in Ireland for distinguishing between footpaths and pedestrian streets (which are consistent with other countries I have mapped in) are based on a combination of width and "streetiness". Where you see the word "wide" used as a criterion in this context, that should be viewed as wide in the domain of pedestrian ways. So for me, anything above about 4m width is already a strong contender. Streetiness for me is a mixed bag. Being named a street is a strong indicator, and being flanked by buildings likewise. Being historically a city street (often dating from an era before motor vehicles, so could still be quite narrow), likewise. There are grey areas, and some of them probably even occur in Cork near where we are talking about (I'm thinking about some of the alleyways to the north of Patrick Street, say, French Church Street). I think that those are correctly tagged as is, mostly for the sorts of reasons I mention above. 