You marked this as off-topic, but I think it’s quite on point, as it touches on one of the lines of thought that always seems to derail discussions about path tagging:
In its most basic sense, shared use path is a design concept about accommodating both cyclists and pedestrians with the same ribbon of pavement. It‘s about enablement and comfort, not necessarily about rights and restrictions. One can argue the concept is flawed because the two groups have fundamentally incompatible needs, or that they pose a danger to each other, or that it’s a waste of public funds, etc. But who are we to criticize the design concept as flawed, solely on the basis that it breaks our chosen data model and its assumptions about access restrictions?
The sign is not the way. To the extent that the shared use path design concept aligns with some law or sign, this is incidental to the task of identifying the path. Quirks of legislation only present a problem because we mistake a sign for what the sign symbolizes. I think there’s been a lot of confusion about shared use paths because the highway=path proposal conflated design characteristics with legal access, which naturally comes from specific laws and correlates to specific signs. Ideally, a specific sign code should be completely irrelevant to answering the question, “What is it?”
As far as I can tell, jargon terms like shared use path and multi-use trail were originally popularized in the U.S., where shared use paths are very popular, even though pedestrians are virtually never excluded from bike paths with very few exceptions. So what’s the difference between a shared use path and a bike path? Marketing. Naming. Your level of interest in urban planning. Most laypeople traditionally associate bike paths with pedestrians too, so they don’t have a problem with the fact that most are tagged as highway=cycleway (apart from the ones last touched by people who mistook the Vienna Convention signs for pretty icons).
Granted, not every country has the same situation on the ground, so it’s understandable that cycleway doesn’t scream pedestrian infrastructure to everyone. One of the issues the highway=path proposal sought to address was this bias toward cycling. (Or is it a bias in favor of pedestrians?) This isn’t a totally bad idea – it eschews a layperson’s classification, which might be too parochial, in favor of an urban planner’s more technical classification. If the proposal hadn’t tried to accomplish too much at once with a single tag, maybe mappers would’ve been able to rely more on intuition rather than pulling out the traffic sign manual.