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

In Act Four of
, 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.