Why does store-bought peanut butter in a jar have so much more oil than fresh ground?

When I buy fresh ground peanut butter, it has a very dry, paste-like texture with almost no oil. It can sit on my shelf for a week in warm weather and no oil separates out.

When I buy peanut butter in a jar, it has a layer of oil on top. Once this is mixed in, the texture is creamy and oily at room temperature.

The label claims that the jar contains only dry roasted peanuts, nothing more. This seems to be the case for all brands I've seen. Where does all the extra oil come from?