The fallacy in the concept we're discussing here is assuming that OpenStreetMap is being held back by the speed with which we can add infrastructure geometry (I'm specifically excluding mass doodling of buildings as that is a topic on its own, and, hey, google does just fine without buildings nearly everywhere).

Given reasonable quality aerial imagery (on which automatic detection a la Facebook depends too) the limiting factor for years in OpenStreetMap has been meta data collection (names, road attributes, POIs, addresses and so on). Humans are quite fast and good at tracing roads and the couple of minutes it takes to add a few dozens of streets is just inconsequential compared to the time and effort it takes to go there and actually survey and add the meta data.

Now despite some bloggers, that themselves haven't noticed that OpenStreetMap is very different than in 2007 (but you know xkcd 386), claiming that OSM is standing still, the OpenstreetMap community is quite welcoming to new and better ways of surveying and obtaining data. Mapillary and now OSV have made lots of aspects of meta data collection easier and faster and have found wide spread adoption in OSM including automatic sign detection and so on.

But even with such advances, gathering and entering the meta data is still by the order of magnitudes the dominating time consuming process in OpenStreetMap (and for what it is worth in any mapping activity).