What appreciation, if any, does Higgins show for Eliza's hard work and achievement in Pygmalion?

In Act Four of Pygmalion, Eliza, Colonel Pickering, and Professor Higgins have just returned from successfully passing Eliza off as a duchess at a series of socially significant events (a garden party, a dinner party, and the opera). Despite the tremendous success of her performance, Higgins shows no appreciation for Eliza's hard work and achievement. While Higgins relaxes in his chair and discusses the evening with Pickering, Eliza busies herself with making him comfortable...

In Act Four of Pygmalion, Eliza, Colonel Pickering, and Professor Higgins have just returned from successfully passing Eliza off as a duchess at a series of socially significant events (a garden party, a dinner party, and the opera). Despite the tremendous success of her performance, Higgins shows no appreciation for Eliza's hard work and achievement. While Higgins relaxes in his chair and discusses the evening with Pickering, Eliza busies herself with making him comfortable (fetching his slippers, etc.), which also goes unnoticed by Higgins.

In fact, the two gentleman speak about Eliza as if she was not present in the room. When Pickering first mentions Eliza having done "the trick, and something  to spare..." to Higgins, Higgins simply responds, "Thank God it's over!" In a continued statement on the night, Higgins comments:

     "I knew she'd be all right. No, it's the strain of putting the job through all these months that has told on me. It was interesting enough at first, while we were at the phonetics; but after that I got deadly sick of it. If I hadn't backed myself to do it I should have chucked the whole thing up two months ago. It was a silly notion: the whole thing has been a bore... When I saw we were going to win hands down, I felt like a bear in a cage, hanging about doing nothing. The dinner was worse: sitting gorging there for over an hour, with nobody but a damned fool of a fashionable woman to talk to! I tell you, Pickering, never again for me. No more artificial duchesses. The whole thing has been simple purgatory."

With this speech, Higgins manages to singlehandedly dismiss the efforts that Eliza had put into developing her duchess "character" and improving her speech and self. Instead, he focuses on the tremendous "consequences" he's faced as a result of the experiment: boredom, the waste of time, etc.

Higgins' first direct address to Eliza in this scene is a mundane domestic order to turn off the lights and to inform the housekeeper that he would like tea in the morning instead of coffee. When Eliza reacts violently to this, Higgins hurls his most presumptuous insult yet: "YOU won my bet! You! Presumptuous insect! I won it!" Higgins--charming fellow that he is--not only fails to appropriately recognize Eliza's efforts, but also takes sole credit for their joint triumph.