It takes a certain amount of trust and integrity to live up to a contract. Neither trust nor integrity can be found in abundance in present-day United States. From Charles Hugh Smith at oftwominds:
The Social Contract is broken not just by wealth inequality per se but by the illegitimate process of wealth acquisition
I do not claim any expertise in social contract theory, but in broad brush we can delineate two implicit contracts: one between the citizenry and the state (government) and another between citizens.
We can distinguish between the two by considering a rural county fair. Most of the labor to stage the fair is volunteered by the citizenry for the good of their community and fellow citizens; they are not coerced to do so by the government, nor does the government levy taxes to pay its employees or contractors to stage the fair.
The social contract between citizens implicitly binds people to obeying traffic laws as a public good all benefit from, not because a police officer is on every street corner enforcing the letter of the law.
The social contract between the citizens and the state binds the government to maintaining civil liberties, equal enforcement of the rule of law, defending the nation, and in the 20th century, providing social welfare for the disadvantaged, disabled and low-income elderly.
Critiques of “trickle down economics” focus on income inequality as a key metric of the Social Contract: rising income inequality is de facto evidence that the Social Contract is broken.