The US government doesn't necessarily hold data with this level of detail. If they did it would be (in theory) in the public domain anyway. Remember the differe

The US government doesn't necessarily hold data with this level of detail. If they did it would be (in theory) in the public domain anyway. Remember the difference in size between the US and European countries. As for why other governments even have to "release" such information, it's historical and surprisingly hard to change. The UK government holds possibly the most detailed map in the world covering every inch of Britain. But after 2000 when GIS based products started to take off people discovered that none of this data was available to use. OSM was created specifically to give the UK some open geographical data because there simply wasn't any and campaigns to the government were taking too long (the government data still isn't fully open).