GladesGuru, I've been on the minority side in most of these parking lot debates, when I've participated.
Mainly because I think preventing people from disallowing firearms from being included as part of the contents of an automobile that accesses their own property amounts to a power grab by government. Government power is always a threat to our freedom, and at some date can always be turned against RKBA, as has traditionally been done by governments.
But I think you make a very good point, one that comes close to convincing me: if businesses become monolithic in their prohibition of guns in their parking lots, then indeed our RKBA would be infringed. For instance, I routinely drive up and down the east coast with various guns aboard my truck - what if all the fueling stops decided your vehicle coundn't contain a gun while you were fueling up? No question that RKBA is infringed at that point.
What I'm saying is that if we do get to that point, or something like it, or if you can convince me that we're already there, then I'll sadly agree that such laws are absolutely needed. For the time being, I'm not convinced that parking lot bans are monolithic though.
BTW, I would see the need for it as somewhat analagous (insofar as it represents an infringement on freedom) to the need for the original civil rights legislation prohibiting discrimination on the basis of race. In my mind, Americans should have the freedom to refuse service customers arbitrarily, without qualification. Unfortunately, we refused service on the basis of race, monolithically, this lack of virtue resulted in a loss of a bit of our freedom, the freedom to choose part of our customer base. And in turn, the government assumed a little more power, something that I oppose on principle, but something that was necessary in that case.
The article doesn't make clear how the law applies to residential property, or whether it differentiates between various types of businesses.
As an aside, I thought of another analogy. If you enter the Bahamas by boat, you are absolutely not allowed to be armed. However, the Bahamas considers firearms to be a legitimate part of a ship's equipment, so they do allow firearms on the boat, so long as they stay on the boat under lock and key. It's an enlightened policy, IMO, and one that other island nations do not necessarily follow.
I haven't had a chance to go fishing in quite a while, sometime soon, no later.