How would an ordinary layperson describe this configuration? Do they consider it to be three different paths that happen to be conjoined without an appreciable barrier between them? Or two paths, each with a left and right? Or only one, divided into four lanes? Does the surfacing only remind people of where bikes can go, or does it also suggest that the walkways are subordinate to the bikeway, analogous to the road to the west that has a sidewalk?
Admittedly, :left/:right is a simplistic model that only scales to ways with two sides. (There’s also :both_ways, which essentially means “center”, but it’s terribly confusing in the context of a shared use path on which traffic flows in both directions throughout.)
Your example reminds me of some gnarly edge cases involving driveable roads. In Dayton, Ohio, Marl Road allows walking and cycling in either direction to the left of center, while apparently driving is allowed on both sides of the road in the usual manner (driving on the right).
Much more commonly, a fast food restaurant’s drive-through backs up into a parking lot, squeezed between the parking spaces and parking aisle. Despite the lack of physical separation, I usually see mappers draw a separate service=drive-through way, because the :lanes extension isn’t a natural fit for primary keys or the secondary keys that iteratively refine them.
Sometimes it isn’t even possible to describe the configuration in terms of lanes, as in this restaurant drive-through, also in Dayton:
Or this pharmacy drive-through outside Cincinnati, Ohio:
Tags can only represent geometry so well before they start to break down and we have to map separate ways, theory be darned. But the case of a segregated path is so common and usually so straightforward that it probably deserves a simple tagging scheme, even if it can’t handle more complex cases.