Reprinting and attributing is allowed. Copying and not attributing it isn’t, because besides the whole theft aspect, it implies that you yourself observed or researched the given assertions.
I don't think attribution is as necessary as you make it sound like at least when it comes to AP/Reuters stories used by news orgs that are in partnership with them.
Generally you'll see that when an article is simply copied from AP or Reuters, it's credited that way; if it's used as a source or being rewritten, it'll be credited with a phrase something like "Wire stories from Reuters were used in this report".
