I honestly don’t know if DDG uses Google, but, since it advertises as an alternative to google, I have been using it with very good search results. I tried Bing for a while and was not as impressed.
I agree as Bing misses a lot and is not as comprehensive as Google in scientific images. I hate Google and its political ideology and only use it as a last recourse.
DDG is Bing. The bulk of their search results come from sending the query to Yahoo. But Bing is, and has been for some time, handling searches for Yahoo.
The only thing you get out of DDG is some degree of anonymity (which is a good thing).
Regarding your comment about Bing, Bing and Google have been neck and neck in search quality metrics for years now.