I read a ton of Usborne and Dorling Kindersley books and these were exactly the sorts or subjects they fixated on. I suppose it's probably part of some long-established national curriculum.
Where I live, people often (conspiratorially) complain that more serious subjects were not covered in school, but the only things I can't ever really remember covering involved South-and-4th-of-July-American history. We didn't really cover Africa outside of the 20th century, either.
To be honest I think American schools are the only ones who really give colonial history the attention it deserves because it's the basis of their entire country and then goes on to fill out the comparatively boring eighty or so years between the end of the Civil War and the start of World War II. I find most people I talk to from the UK who are aware of some aspect of colonial history are either apologists for the British Empire or have this imported view common in North American (and especially Canadian) universities that the British were this uniquely nefarious force of evil. I suppose the historically curious ones just spend their time studying the Norman conquests.