You're talking about highly-focused, or micro, search. Yeah, Google doesn't seem to do that very well. They have a few segments, like book search and image search, but it's not specific enough.

One thing I search for sometimes are code examples in a particular language. Search for something in C on Google and you end up with lots of stuff for C++, C#, etc... Github, with its large repository of public code, lets you filter by programming language, and is much better than Google in these cases.

Bing copies Google. DuckDuckGo returns different things than Google, but otherwise is a copy. There's no micro search engine for specific topics and sub-topics, outside of site-specific search. Market opportunity...