And, presumably Bing tracks users and uses that data to improve its results. When you use DDG, you're just being tracked as "a DDG user" instead of "a Bing user with cookie=0x23987438743". (I don't know if that's true or not, but it's my current understanding of the situation.)

I think the problem with tracking is not the intrinsic action, but rather the fact we call it "tracking". Tracking is the technique you use to hunt and kill animals. Showing Java results to Java programmers and C# results to C# programmers is a little different from that...

No it is not.