People who advocate for small government often fail to realize many purposes of government such as this. Another purpose is literally to protect us from enslavement by our fellow countrymen/countrywomen/countrypersons.
There is a tremendous amount of conservation effort from many privately funded, non-profit organizations. One could make a convincing argument that The Nature Conservancy, WWF, Sierra Club, et. al. do more work protecting our wildlife and wilderness areas than the government's neglected BLM land.
Perhaps small government advocates prefer philanthropy over authority?
Government needs to be at least as big as the corporations it seeks to regulate, or things get squirrely. This is obviated by problems like campaign finance, Trump, fossil fuel subsidies, etc.
Why?
Does the board need to be as large as the company?
Seems like this would eventually lead to (or read as), "The government needs to be at least as big as the sum of the corporations it seeks to regulate".
I agree that things get squirrelly when corporations (or NGOs, even) wield more power than governments. That's most obviously an issue when large global corporations mess with small countries. Or small states in the US, for that matter.
While it's also an issue even in the US overall, one hopes that antitrust enforcement would kick in before total domination.
The government isn't great at managing forests, but if had my way it would already be done.
A government brings with it the ability to actually enforce laws, and I think there are sufficient examples in world history as to why the ability to enforce is just as important, if not more, as the ability to legislate. That's partly why we now have the Constitution instead of still using the Articles of Confederation.