Don't go near the water (not)!
The 3d DCA held that this was a violation of state antitrust laws -- the City's arguments about being authorized to limit competition under its general authority to regulate the streets was, well, not sufficient to get it past federal antitrust scrutiny, which in turn left it liable to be found in violation of the Florida law. The court held that the City would be liable for attorney fees and costs under the state statute.
But that's not all! The court went on to hold that summary judgment against Duck Tours' commerce clause claim under s. 1983 was improper -
"Reading the summary judgment record in the light most favorable to Duck Tours as the nonprevailing party, the ordinances constitute a burden on interstate commerce that is clearly excessive in relation to the putative local benefits. "
Yet another case of a local government pretty blatantly over-reaching and the refusing to say "my bad" when busted.
Here's the case in PDF format: