I'm not familiar with Proposition 65. Perhaps it doesn't address issues that are important regarding food regulations.
What I do know is that Mexico shipped a bad batch of strawberries to the United States and people got sick. When an investigation insued, it was found that Mexico had irrigated those strawberries with water containing some level of fecal matter. (I forget now if it was human or not, but I believe it was.)
We have developed some important guidelines for food safety in this nation. Other nations are not reguired to observe those guidelines, even if they are shipping that produce into the U.S. I think that's a problem.
Do I want big-government dipping it's fingers in everything? No I don't. When it comes to food safety I think it's important for government to do so.
IMO the restaurant inspection process in Los Angeles has helped to clean up some pretty despicable restaurant practices.
None of us wants big government, but there are times when regulations are reasoned.
House votes to dump state food safety laws, San Francisco Chronicle, March 9, 2006
Prop 65 was the Safe Drinking Water and Toxic Enforcement Act of 1986. In addition to product labels, it's also responsible for all those signs warning you of cancer and birth defects. (At bars, in garages, paint shops, etc.)
Private certification can accomplish even more, and they're actually accountable for their verification, unlike the FDA or USDA. There's no reason for government to be in the food safety business.