One reason we wouldn’t hear about it if Hussey was a working class woman from the street is because she would be less likely to be in a position of authority or note. It’s more newsworthy because it’s linked with the royalty. Someone less of note making similar comments in the pub isn’t. However, such people do complain in less newsworthy contexts.
As for ‘agendas’. Everyone has their biases, but you seemingly like to point out agendas among others in a dismissive way when you have an agenda yourself.
I do agree that education on why it’s racist would be a good response, but racists would use anything as ammunition. Nothing is a legitimate response to racism for them, so they’d use it as ammunition no matter what.