Trademark law addresses confusion in commerce. So if someone boarded a flight based in part on the flag of the destination, hoping to reach the sunny shores of San Diego but instead landed at the cold shores at Duluth, then perhaps whoever drew up the ad for that flight might be liable for something closer to fraud rather than trademark violations. Maybe the Visit California department could raise a trademark challenge, but that’s an uphill battle because it’s not disallowed to use a state flag in other situations.

Texas Roadhouse, a chain of BBQ restaurants, flies the Texas flag on their buildings. And while they do heavily lean into the whole Texan thing, no one is under the impression that Texas Roadhouse is an official arm of the State of Texas, to proselytize the BBQ religion to people far and wide, or some such.