Why do the authors of the text argue for a national rather than a state or local

Do you have the text in question, and can it be posted/transcribed here?

A national approach, in theory, allows everybody to be on the same page. Local or state approaches are much more specific, and effectiveness can range from extremes (good or bad) across localities. It's sort of the difference between having a national park and a state park: the national park is protected from the fluctuating politics of the state, which provides a more permanent stability to the park itself. Otherwise, states could, on relative whim, simply destroy a park for housing development and logging because it is convenient, whereas the national tag attached to the park protects it for the long term.

It's from the Social Problems 13e textbook...

To answer your question:

• Evaluate the impact of local control.
• Use examples to show why local control is not efficient.
• Assess what the impact would be of a national approach.
• Speculate about what it would take to forge a national approach.