I don’t know if you’re correct about the tort implications here. If a place of public accommodation is openly declared to be a “gun-free zone,” the any liability on the part of the person or persons responsible for that policy would be heavily offset by the failure of any aggrieved parties to reduce their own risk. In other words, a person who conducts business in such an establishment knows full well what the risks are, and shouldn’t complain when something like this happens.
That is one way to look at it. However, the business has a greater duty to provide a safe environment and take steps to avoid foreseeable dangers created by their policies. Every mass shooting has taken place in a place that bans guns. Several perps are on record as explicitly picking a place guns were banned to do their crime. By banning guns they vastly increase the danger to patrons and employees.
The customer or employee does not have the same responsibility as the business to know the risks of entering the establishment. For example, amusement parks budget for a certain number of injury wrongful death payouts every season. The patrons don’t have as great a responsibility to know the extent of the possibility of injury or death as the park,
In my state a place of business can post a no weapons on the premises and it has the force of law.
I carry.
If I can't carry I don't go.
When I go to the bank I use the drive through.
Churches are legal carry unless they post a sign. When that happens I guess I won't go to church.
Stupidity happens. Guns are a great thing to have on site, it protects all.