There are several reasons to drop the article. One is that some institutions, governmental or not, are never referred to using the definite article. Another is that the article can get dropped as a consequence of familiarity with and/or personification of the institution. Of course, NewsHour and the like may simply impose a stylistic preference to remove nonessential words.
We often apply the definite article to the names of governmental organizations when the type of organization is part of the name (ministry, office, committee, et al). This is natural, since it sounds like we are specifying one organization of a type— National Park Service, which happens to be the name of the national park service; likewise the National Health Service or the Department for International Development. Where the organization is "branded," however, this is not the case, and we do not use the article: Parks Canada, Medicare, USAID (even though we would write out the United States Agency for International Development).
As with the names of countries and geographic features, there are no absolute rules in naming institutions. It is simply Gosbank but always the Bundesbank; someone attended North Carolina State University but attended the University of North Carolina (and yet attended UNC). With proper nouns, whichever usage becomes popular is that which becomes accepted, and sometimes (e.g. [the] Ohio State University) it is a muddle.
Dropping the article is quite common in some other professional communication. People who work with a particular organization may personify it, especially in internal circles, and as English does not use articles for personal names, the article may get dropped.
This is more obvious where an unofficial nickname or abbreviation is used. A large company, say ABC Inc., might organize its employees into divisions. A press release or business school case study about them would write out the full name: the ABC Marketing Division and the ABC Product Development Division.
Suppose you worked for ABC, and you interact regularly with those divisions as well as with some outside actors: the Las Vegas Chamber of Commerce, the Greater Boston Chamber of Commerce, and the U.S. Bureau of Indian Affairs. Your internal emails will get simpler over time, indicating each group with the minimum of identifying information: there's good news out of Marketing, you should talk to PDD, send the proposal to Vegas but not Boston, we're waiting on approval from BIA. Obvious all those groups are made of up many different people doing many different things, but in terms of their interaction with you, they might as well be monolithic. It doesn't matter if it's Sandy from PDD or Chris from PDD, you just need someone from PDD.