The Economist originates and has primary readership, in the USA. In that country, the term "America" is used to refer to "United States of America." When referring to the American continents, the common terms are "Americas" (note the plural form) or the explicit forms North, Central, and South America. Most people in the United States are aware that the United States does not span the entirety of any or all of the American continents. As a simple example, most Americans are aware of the country north of the USA border called Canada, which is also in North America.
Someone will probably downvote you for making the irrelevant mistake saying US vs UK, but your point is absolutely correct that “America” is colloquially the name of the USA, not a continent or set of continents, in both US and UK English.
I suspect OP knows this, and is fighting a battle to try to change how Americans speak their own language — it’s not rare, in my experience, for people in other countries of the Americas to be annoyed by this usage.
Hope that helps.