“You would have already noticed that the first few non-ad results are SEO optimized sites filled with affiliate links and ads.”
People append “reddit” to their searches because it’s the only way to find a human who isn’t selling something. Google gets paid for the ads at the top and for the ad networks on the spam below them. It has no reason to fix a results page that pays it twice. Reddit, meanwhile, still can’t build its own search box.