Class identities are much weaker in the US: they're much more tightly tied to economic status and are thus fungible (almost anybody can move up or down the US class ladder by gaining or losing wealth.) We have a "cultural class" system as well, but it's similarly weak (with opportunity, nearly anybody can join the starving intelligentsia).
The author is in the UK, where class identities are much stronger and are not intrinsically tied to wealth (but are frequently associated with wealth, thanks to generational privilege).
An upper-class British acquaintance recently related to me that they'd never eaten certain foods that Americans think of as "quintessentially" British, because those foods are lower-class foods. They weren't afraid of eating them or snobbish about it, it just hadn't occurred to them that it was part of the international perception of their culture (because, to them, it just isn't their culture).