the ~ means roughly, so the quiz is about countries with roughly 10% of their population within their capitals. Not at least 10%. Places like those you mentioned have 100% (except luxembourg) of their population in their capital, which is far from 10%
Awesome. For people who like pedantic technicalities: the combined populations of La Paz and Sucre = roughly 980,000 = roughly 10.8% of Bolivia's population :-)
Peculiar that places that have at least 10% such as Singapore, Luxembourg, Vatican City, Monaco are missing.