"It's a transfer of wealth of hundreds of millions of dollars from Californians to the pockets of grocers and their union bosses," Daniels said in a phone interview. "It's exporting 2,000 jobs from California to China where they manufacture the reusable bags."
Calling the law "a gift from the legislature" to grocers, Daniels estimates grocers will make at least 5.5 cents from each paper bag sold.
"It's particularly difficult on those with fixed incomes or those who are struggling financially," he added. While people on public assistance do not have to pay for the bags, others struggling financially do not qualify for the freebie.
Read MoreCalifornia becomes first state to ban plastic bags
Many members of the Neighborhood Market Association, a group of independent retailers in California, Nevada, Arizona and the West Coast, don't plan to charge their customers who often live paycheck to paycheck for the bags, said its president and CEO, Mark Arabo.
He stressed that the law presents a headache for smaller grocers who don't have the resources for compliance with the ban and that it could spark an uptick in stealing.
"We see that when folks come into grocery stores with their own bags, we see an increase in shoplifting," Arabo said.
One supporter of the law, Ron Fong, president and CEO of the California Grocers Association, insists it won't have unintended consequences. Because grocers have faced plastic bag limitations in various areas for years, they've had time to see what works and what doesn't, he said.
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"There's an initial learning curve—more than anything, it's getting our customers used to the idea," he said by phone. "Our stores have thought this out."
As far as the criticism that the ban lines grocers' pockets, Fong insists they won't be profiting from the new law and need the money to cover costs.
On a lighter note, Fong also addressed potential concerns from animal lovers, who now face possible additional expenses for tidying up after Fido multiple times per day, saying there are other options and produce bags are not impacted.