But how would people know?

When was the last time you saw a .co that wasn't an url shortener or a rare startup that couldn't get a .com? There is a major trend in the domain market that is crystalising country level markets around their local ccTLD and .com. This is a move towards bluechip TLDs that is very similar to some trends in 2001-2004. The .info gTLD has been losing registration volume for most of this year. The .biz gTLD is just puttering along. The .mobi sTLD is also treading water.
The usage numbers that COInternet publishes are inaccurate. They classify redirects to Godaddy's PPC lander page for undeveloped domains as an ordinary redirect. This makes .co usage look better than it is in reality.
After about two years or so, the signs of development start appearing in a new and healthy TLD. At least 45% of .co is PPC parked and probably another 12% would be generic holding pages. Development might be in the region of 18% but that's without analysing the dataset for clone websites. And that's without even checking for abandoned/half-developed websites. There may be startups using it but they are few in number and the reality is that COInternet needs to kickstart development among the Mom and Pop businesses that form the core of any well used TLD.
I haven't called the .co ccTLD a Bubble TLD yet but it is close to becoming a Dead Zone. That Sedo auction should have been a wakeup call for some of the more extreme .co fanboys and rather than just dumping their domains on PPC landing pages, they should try develop some.
Regards...jmcc