Clarifying, I have no problem with adding unsigned=yes tag to such routes. Maybe someday the whole 'net of these routes comes down (are deleted). Maybe destination + infrastructure “rendering of routes” (in colors or something…) is OSM’s future here. (Different than how we do things now, but not by much). I don’t know, but Richard’s research into the syntax of unsigned=yes gets nods, me included.
OSM might see growth in adding nodes for these newer signs. And maybe even people are cooking up neat routers and renderers that are smart to this sort of tagging et cetera.
And, we’re on hold for now from SFMTA. I’m in no hurry but no reason to dilly-dally. Our tagging can handle it.