Well I don’t think much of the OP’s argument. “America”, whether we like it or not, has come to be popularly synonymous with “United States” among English-speaking audience. There’s little risk for ambiguity because Western news agencies almost never use “America” alone when referring to the region or continent — they would say “American continent” or “North/South America”

In 50 years, when the U.S. has decided to call itself something else, then yes, this CNN breaking news headline will be ambiguous. But breaking news writes headlines for its current audience, it’s not meant to be a taxonomically accurate index.