What could be more unequal?
What I like about them is that both ups and downs are really moral equals, merely in different situations of power. In our current bleeding-heart culture the simple fact of inequality casts those upstairs as hypocritical oppressors and those downstairs as morally upright victims. But because the Brits --whose faults do not include sentimentality-- make good drama, the flawed humanity of both sets is more than readily apparent.
In America in the last several decades, for example, the mere fact of having black skin, once a mark of inferiority, now carries the automatic cache of moral rectitude. And by inane contrast, white skin, a mark of privilege, now implies some kind of ethical flaw. Which is bullshit. Just because someone treats you badly doesn't make you good. Merely badly treated. Both nice people and scoundrels can be upstairs and down.
If can remember back to the old "Upstairs Downstairs" --which holds up very well after forty years-- ask what the world would be like if the Family and the Servants switched places. Might not only not be better, but even worse. Who'd you like to be charge: Miss Elizabeth or Sarah?
Sarah, poor and uneducated, forced by that condition to live by her wits, is a narcissistic and histrionically manipulative sociopath, a compulsive liar living by resentment and illusion, without any loyalty. If you're looking for class solidarity, don't look at her.
Her upstairs "sister in spirit" is Miss Elizabeth who combines self-congratulatory social conscience about women's rights and the plight of the poor with an impenetrable snobbery and spitefully arrogant sense of superiority. She is quite capable of chiding her cad of a brother for leaving things around for the servants to clean up and then dressing down a housemaid for dressing up above her station, utterly deaf and blind to the conflict.