Oh man, I definitely thought the greyed-out tags were essentially applied for most practical applications!  Oops.  The app I use that interacts with OSM uses the assumed tags in most cases and very specifically names the cases where it requires the tags to be actually set - I guess it's a little fancier than most?  Seems strange to have the different types of paths with their default tags if the default tags aren't applied!

I've been going with a lot more highway=path (especially over highway=footpath) ever since I learned that LA changed the law to allow bikes on sidewalks and other traditional footpaths.  It seems better to me to keep the delineation between a designed cycle-and-foot-path and a path where cycling is allowed but wasn't considered in building the path - and for the purposes of the app I'm using, highway=path will add it to the cycle  map whereas highway=footpath won't.  Then again, if I start taking the time to name specific permissions, I think that would probably overrule the filters for type of path.

In the case of the bridge and the path it connects to, as an example - it didn't show up for cycling in my app (or for walking, actually, due to one of the specific filters for random "highway=footpath"s), but if I'm correct it will once the map updates later this month.  (I actually will learn quite a bit about how effective my editing has been after the next update - some of my work made it into the last one but the majority will hit this next one.  Maybe the default tags don't work as I thought!)