Earlier quoted context omitted.
It's a super tough problem. Even Google Maps messages you that it's a feature in progress (paraphrasing of course), and they've had years of a head start on this.
You know that got me thinking, biking rules vary far more than for cars. Depending on your location, pedestrian traffic, streets, street traffic, etc. It might be best for you to be on the sidewalk. Or maybe you should instead be on the road since the road is only 25mph and there's pedestrians on the sidewalk. Maybe there's a bike lane, maybe there isn't. Maybe a town has a law saying you HAVE to bike on the road. Ar…
They have elevation, private/public roads, road surface, bike lanes, etc, and routers can take it into account. Of course, that doesn't really take into account varying laws, but that might be reflected in the maps themselves (private/public places, bikes allowed/disallowed, etc).
See also https://www.opencyclemap.org