Why is Google full of spam?

I understand that Google is fighting an uphill battle against spammers, but it really puzzles me how search results for very concrete queries are so obviously full of span entries. I just searched for kCGPDFContextAllowsCopying and expected to find examples where this symbol is used in the Apple SDKs.

The first result (as expected) points to the official Apple documentation (which sucks by the way, but that's not my point).

The second one gives me a Stack Overflow question, which wasn't really helpful. Below that in smaller font size are other results from Stack Overflow. One of these happens to answer the question I had, but I couldn't see this without clicking on the title, because these results are shown without text excerpts.

After that, it goes downhill very quickly with different one-to-one ripoffs of the (non helpful) SO result mixed with some translations of that article to languages I don't understand (and cannot even identify by the symbols used).

Really Google, with all your machine learning foo that's the best you can do? Why not show multiple results from Stack Overflow if they are relevant?

Sorry, I just needed to vent, but maybe someone can enlighten me what's so hard in detecting that a page just copies articles from Stack Overflow.