Few states require lunch or rest breaks, if any. I know that for most employees over the age of 18 in even more politically liberal states like New Jersey do not require rest breaks. Of course, many states regulate such for minors, but few for workers over the age of 18.
I've included a link to a Department of Labor chart that gives requirements for each state on meal breaks. It's a pretty short list: California, Colorado, Connecticut, Delaware, Illinois, Kentucky, Maine, Massachusetts, Minnesota, Nebraska, Nevada, New Hampshire, New York, North Dakota, Oregon, Rhode Island, Tennessee, Washington, and West Virginia.
For rest breaks, the list shrinks to California, Colorad, Kentucky, Minnesota, Nevada, Oregon, and Washington.
Perhaps few regulate is because most employers voluntarily give rest breaks to employees to make work more bearable. Perhaps few regulate because unions, often providing the strongest labor law components in states, don't really care if non-unionized labor is forced to receive breaks, but really works hard to ensure that its own members are protected through contract agreements and bargaining. Regardless, I hope this information helps.