The sin of greed (from the 7DS) in embodied by Mr Birling. He is used as a construct by Priestley to place emphasis on greed and selfishness being capitalistic traits.
"Wretched girl's suicide"
Derogatory tone - signifies the cruelty & disregard the UC had for the WC. The WC were dehumanised & treated with disrespect.
Clarification of "girl" demonstrates how women were viewed as inferior within a patriarchal society.
"Wretched" - suggests that the death in an inconvenience & nothing else. The Birling's don't consider Eva's death as their concern - there is no impact or importance behind the death of this girl.
"Lower costs & higher prices"
WC is exploited by UC - they're an expense, a commodity.
Capitalism - focus of the UC is the production of their wealth.
Highlight's the selfishness of Mr B - he uses the union between Sheila & Gerald as a business contract. Shifts the conversation to focus on his materialistic desires. Reinforces his role as a capitalist.
Family bonds are weak as Birling cares more about money. The Birling's are shallow, seemingly only bonded by wealth.
"It's my duty to keep labour costs down. Our labour costs."
Personal pronouns represent the individualistic nature of Birling and by extent, the ruling classes in the patriarchal society of 1912.
The fact that he sees it as his "duty" suggests that perhaps he is being conditioned into being selfish by the pernicious effect that capitalist society has.