Uncle Buck, in general I agree with you.
However, there is some disagreement about whether a public entity, such as a store, really counts as somebody's "front lawn."
IE, if you are open to the public, you already give up a lot of the rights that would attach to your home.
I don't have to allow Basques, algebra teachers, country singers, Lutherans or mimes into my home if I don't want to. (My father-in-law is Lutheran, guys, I'm just using random groups, and have nothing against the ones I've listed... except maybe the mimes.) But if I open a cafe, and decide I don't want to allow people in because they belong to those groups, it's a two-sided coin. On the one side, I can refuse to serve anybody in my establishment; on the other, as a public entity, I am liable for lawsuits and loss of license if it can be proven that I have discriminated against those groups (again, with the possible exception of mimes).
So there is a potentially valid argument that a business that is open to the public does not have all the rights that an individual would have. IE, my second amendment rights may carry, or perhaps should carry, more weight at a public market than they would at the business owner's home.
The problem with that whole approach, though, is that (at least in at-will states), employers could come up with a host of other reasons to get rid of an employee who was trying to force such an issue.
Therefore, I still think the only real fix to the problem is tort reform. Take away the sword of liability hanging over the business owner's head, and much of the motivation for firearms bans will go out the window.