My guess would be that there are three things going on a least;
One is that news outlets are loath to let Google crawl them and post snippets, they argue that Google gets the 'benefit' without paying for the content. (this was used in a couple of lawsuits)
One is that Google may provide the advertising feed for news outlets that are shown, thus a double benefit to Google is that you go to their news aggregator, and when you pop off into a news story you continue to be served Google ads.
And finally, there is the polarization of people's news intake through a limited number of sources. Per my experiment I found after deleting the new sources I found offenses Google was unable to come up with additional "interesting" news sources, they just didn't crawl them or have access to them (or they don't exist I suppose). Regardless of the reason, the additional wasn't in their index to serve up.
Their algorithms can suggest amazing insight at times, but when you suddenly get stuff like "Local council changes bin days in Huddersfield" it's clear they have a long way to go to understand news relevance, especially when you were just passing through.