I'm normally one to champion a homeowner's rights to reduce trespassing, loitering, and destruction of property, and I do understand where the homeowners in this case are coming from. I have a little turd of a neighbor who revels in illegally driving his four wheeler across my yard but the police say I'm in a catch-22; unless they are camping out in my driveway waiting to catch him, they can't arrest him for it, and of course they don't have the resources to dedicate to that. He knows this of course, and rides by at random times, flipping me off if I'm outside at the time and tearing mud holes across the lawn.
My point being, the folks in Hollywoodland who are threatening the author and coercing Google and Garmin are barking up the wrong tree. They should be seeking a solution that reduces traffic in their neighborhood without limiting the public's right to visit the park, and without threatening some guy who is already trying to do the right thing by steering tourists away from the neighborhood and towards the approved viewing areas. Just as I can't erect tire-gouging spikes in my yard or hire a thug to intimidate my neighbor into submission, these folks shouldn't be threatening people and illegally marking their curbs and signs to discourage tourists.
I believe it's akin to drenching your sandwich with Dave's Insanity Sauce to catch the co-worker who has been stealing your lunch. If your enjoy eating your hot sauce with a side of sandwich, that's fine. It's the intent of how you're using the sauce that matters.
From Wikipedia:
> Mantraps that use deadly force are illegal in the United States, and there have been notable tort law cases where the trespasser has successfully sued the property owner for damages caused by the mantrap. There is also the possibility that such traps could endanger emergency service personnel such as firefighters who must forcefully enter such buildings during emergencies. As noted in the important US court case of Katko v. Briney, "the law has always placed a higher value upon human safety than upon mere rights of property."
Thinking in those terms, a few spike strips on your lawn should be fine.