Why, a law to accommodate the TV guys, of course. They recommended that Congress require each state to close its polls at the same moment, no matter what time it is. If that were 8 p.m. in North Carolina, it would be 5 p.m. in California. In the first place, since elections are a state matter and not a federal one, the constitutionality of such a law would be, to say the least, uncertain. What is certain is the lack of common sense behind such a proposal.
States ought to establish voting hours that are the most convenient for their voters.
Playing around with the polling times to accomplish any goal except providing reasonable hours during which to vote actually could affect the outcome of the election. Some people might be able to vote at odd hours, and others might not. These data come from the exit interviews of voters in selected precincts. The information is tabulated and projected to determine, before the votes are counted, who will win the state. This usually works, but it has obvious risk.