Yep, before making the eruv, one must first obtain permission(permit) from the local government.
Wait till you see the millions of private cars strewn everywhere on public property, almost entirely for free! It utterly dwarfs the eruv.
False equivalence. Cars are not religious.
Plenty of cars do have religious symbols on or in them, e.g. crosses dangling from rearview mirrors, and that's more noticeable to a pedestrian than the eruv.
It's freedom of religion, not freedom from religion.
Except it's legal to park your car on public streets, as long as you follow the parking laws and limitations that are displayed. On the other hand, you can't throw whatever objects you want on public structures without a permit. They're not the same thing.
The eruv is also allowed by the city and thus legal.