The answer is basic. Here is a simple example.
Imagine you are driving your neighbor to work a couple times a week. Every time, your neighbor asks that you stop at the local convenience store to pick up a bottle of water to drink at work. If your neighbor robs the convenience store while you are in the car waiting, and especially if your neighbor kills someone in the store during the robbery, as you drive away, are you not an accomplice to both the robbery and the murder? The law will look at it as though you are, and you just might have a very difficult time explaining your way out of it.
In other words, the hotel across the street was an accomplice.
In Arizona and some other states where it is free to open or conceal carry, the law states that, if a place of business wants to deprive you of your right to bring weapons into their building, onto their premises, they need to provide lock-boxes for you to place your weapons into, and also provide the security for you that you would have done for yourself if they had allowed you to keep your gun.
If hotels and businesses took security serious, they would provide some REAL security, and check their "guests'" luggage for weapons thoroughly.
The hotel might be considered innocent by standard law. But if people wake up to what is going on, they just might be able to sue the hotel for $zillions in damages. Security just might become an individual thing for all business. And, as somebody mentioned above, arm the populace so that they can protect themselves (It's the people that are too chicken to arm themselves; they would rather die in mass shootings like this.).
Roughly 95% of the people are good people who would never harm anyone. Even among the 5% of bad people, only a few would ever do something like this. If everyone wore a gun strapped to his thigh, people would learn to respect each other, and most of the 5% would be too scared to try anything against the people at all. The few who did would be dead in short order.
Gun respect with an armed populace might take a bit of time to get going... because of how far away from self-protection the people have moved. It will take a while for them to get used to it once it is started. But get used to it, or die. Why? Because gun control means slavery. Death is the greatest form of slavery, because you can't even wiggle in the grave.
