- At least right now, we have a good amount of common-sense information about the world (I don't know when "last time" was for you).
- That said, we have a lot of highly specialized knowledge in various domains, so if you took a random sample of the knowledge base (KB) it may not be as common-sense-centric as you'd hope. But the KB is also incredibly large, so that doesn't mean we don't have much common-sense, just that we have even more other stuff.
- Often for contracts we get paid to construct lots of domain-specific knowledge, even if the project also uses the more general knowledge, so this biases the distribution some.
- Information that's already well-taxonomized is low-hanging fruit for this kind of system; its representation doesn't take nearly as much extra thought and consideration, so it's a faster process, which also biases the distribution some.