Id scrapping news sites is illegal?

Is scrapping news sites is illegal? To my knowledge it is kind of illegal and even if you are scrapping some websites you definitely can't use the data for commercial proposes. Im asking that because HackerNews is clearly doing so and present full articles from other sources in their app (the website only show link to the article) so how do they do it? I find it hard to believe they have permission from the owner of the content as they have links from basically any site in the world