I see where you’re coming from, but I think this is probably unnecessarily strict, when we already tag plenty of pedestrian malls as highway=pedestrian
even though they allow some limited use by motor vehicles. For example, this pedestrian mall in Cincinnati serves an open-air market; it’s strictly limited to pedestrians during market hours but allows motor vehicles to make deliveries or park during off-hours. On balance, calling it an ordinary unclassified street is a bit pedantic and misleading, since the restrictions during market hours are far from the norm for that city:
On the campus of Stanford University, many of the streets around the main quad are considered pedestrian malls, even though the vast majority of traffic is on bicycles, and some motor vehicles are allowed – specifically, the golf carts and other small electric vehicles of a university-run shuttle service that serves disabled students, students who need a safety escort at night, and anyone who needs a ride after an intense party.
It’s cases like these that help to justify the dedicated highway
values. Otherwise, pedestrian malls could just be service roads that disallow motor vehicles, and busways could just be streets that exclusively allow buses, all via access tags.