Since the 1980s, policymaking in the u. s. government can be described as the "politics of scarcity" because

The budget is the main scope of any government. This is because the higher the budget, the bigger the government is.
Since the 1980s, the policy in the US has been lacking funds for programs like health care reform and education.

Based on this:
Since the 1980s, policymaking in the u.s. government can be described as the "politics of scarcity" because it has been lacking funds for programs like health care reform and education.