I don't think this is true. If you compare Obama's daughters against Bush's sons, probably. But against a random white person with no media exposure, unlikely.
> they would have been far wealthier if they'd been born to a comparably wealthy white family.
Again, why are we comparing against comparably wealthy white families? The reason why Obama's daughters were brought up in the first place is because we recognize that they are incredibly privileged compared to the general population, and they don't need more advantages. We don't care whether they are privileged compared to Bill Gate's children or someone comparatively more privileged.