The despicable behavior of the Gresham children in Trolloper's Dr Thorne

I'm not meaning to be or trying to be xenophobic or exceptionalist here but can you imagine an American - much less a character in an American novel? - acting the way the Gresham children do in Trollope's Dr Thorne? The Greshams as noted in previous posts are a "noble" family fallen on hard times (by their measures; they certainly don't seem to be starving to death) because the pater familias has squandered much of the family fortune and the male hair, Frank, has to in their words "marry money" to keep the family on its feet - even if, god forbid that means marrying a "commoner." Ok, that much we can accept - but the plot revolves around Frank's love for his neighbor, the Dr's Mary Thorne, who has no money (or so they think, ha ha, she may yet become an heiress) and no "name" (born out of wedlock, in fact). So Mother Gresham tells Dr Thorn that Mary is banished from their house, where she has been best friends with one of the daughters (as well as Frank's childhood crush), and then when this doesn't entirely work to cool the ardor she orders that her daughters are not to even socialize w/ Mary outside of the gates of Gresham. Appalling and cruel, right? But the daughters hardly chaff at this, it all seems pretty reasonable if a bit sad to them, boo hoo, poor Mary - but not a one says to the mother what she should hear: Screw you, mother - and they should pack their belongings and move out. Wouldn't you do that? I am not saying that Trollope is wrong in his characterization, but if he is right it's an astonishing condemnation of the entire petit aristocracy English culture in its dying phase - and honestly I think any good American democratic young woman, or man, would know what's right and would asset themselves, whatever the risk. And plenty of characters in English fiction would so as well - but Trollope gets right to the rotten heart of the matter.