This begins to fall apart in major cities without OSM volunteers ingesting city roadwork feeds. Of course, something like tomtom wouldn't represent that ideally either without a radio data or cell service...
Waze used to (still does? I don't know as I don't use Waze any more) display dots on paths and as you drove it scored you and also used the data to confirm maps. Is there anything like this in the OSM world?
Drivers in the field can record GPS tracks, and upload/share them through the OSM website. These can then be used either to directly create that road, or by remote mappers to help align satellite imagery, and then remote map visible roads in the area.
Not really. But OSM is a wiki. So there is no central body to "confirm" changes. If you want, you can just edit things as you go.
You can even edit OSM on your phone (e.g. with Vespucci), so you could drive along a road, think "this is totally wrong on OSM", pull over, get out your phone and correct it.
OSM volunteers are pretty crazy, though. A friend of mine spent his time doing linework for North Korean roads. It's a data sparse region for us capitalist pigs. Anywhere, there might be good data where you least expect expect it.