“Somebody at Google is skewing the queries”
Such accusations have been leveled at Google almost as long as it has been around. Every time, it’s shown that the results are just a matter of who’s searching and who’s choosing which result.
In this case, I suspect that “white couple” is probably being searched largely by people who both tend to view content dominated by blacks, and when presented with a range of options for that search tend to pick the blacks. (Consider: if you do the experiment yourself, you’re probably going to search for “white couple” and then click on a black couple - reinforcing the automated results.) In contrast, people who supposedly would tend to select the white results, well, I actually suspect they won’t be searching for the racist term “white couple” at all.
Remember, there’s a whole lotta people out there who don’t think like you. What Google tends to show for results tends to reflect what THEY are searching for & selecting.