I just checked my home address on OSM. My whole subdivision and the major 4 lane road that goes past it was all build 6+ years ago. None of it exists in OSM. This is a well populated suburb of Atlanta.
And regarding satellite view, how would you even imagine volunteers making satellite images? Basically anyone can get a GPS receiver and make maps, but I have yet to see an amateur hobby satellite in orbit. (I guess you could use R/C planes with GPS and cameras, but that would be incredibly time-consuming and not ideal at large scales.) However, even if you could do that, it's just not goal of OpenStreetMap. You can't use satellite images for routing, there is no legend, etc.
And I think that they don't allow external satellite images because of their philosophy on freedom - similarly to you having to explicitly allow installing non-free packages in Debian.
Across the world, I can't answer. Here in Western Australia, one of the largest single states in the world, there's been digital mapping for two decades now, predating the rise of Google maps.
Data from MODIS satellites is downloaded direct from the sats as they pass overhead and streamed to those with an interest. The better quality data comes from the aerial surveys performed each and every summer over populated areas which produce several thousand digital scans of wet negatives (they may have recently moved to high res digital in the planes, I've been out of the details for a few years).
Google didn't develop their mapping tech initially, they purchased the starting technology from Keyhole, a US based company (iirc), it's worth noting that several international companies had equal or better offerings that were considered including our locally developed technology from ermapper which is now owned by Lecia.
http://www.erdas.com/company/news/newsreleases/07-05-21/Leic...
As for volunteer contributions it's been our experience that if you provide data access and annotation tools then many competent people that care about ground accuracy (forestry services, land owners, search & rescue, exploration crews, etc) will happily add value.
Also, the best of OSM is in places like Germany where in some areas they're mapping down to the level of individual trees and lampost locations as well as where animals are located within zoos.
http://bestofosm.org/#best-of-de-berlin-zoo
Using the OSM's online mapping tool is fun. I really enjoyed doing the maps for around my home - it made me look up streets I'd never noticed. I felt I learned a lot about my local area.
[1]: http://code.google.com/p/osmeditor4android/ or Vespucci in the Android Market
Good luck.
Google Maps was first published in 2005, so it's been doing nothing for the "last 10 years"... And during that time they've changed base map data providers several times in most countries (Navteq -> Tele Atlas -> Google), making it incredibly unlikely that such errors would have persisted for the whole time.
I might have gotten very lucky there, but it can't hurt to report it, right?
The good thing is that, unlike Google Maps, you have complete power to update OSM with the correct information for your locale. Get mapping!
Can't you also do that with Google MapMaker (depending on the country)?