This is pragmatically correct, but it doesn't make it just. The city was given policing authority over those lands, too; that doesn't mean they should have the right to torture you until you confess, even if the democratic voters are in favor of that — as they might be, for example, if you're black.
At least in California, counties have zoning ordinances and permitting requirements too.
And in LA, local city councilmen operate as feudal lords in their districts with absolute authority on what gets built and especially by whom.