They might be liable for not adequately protecting the patrons, for example. My uninformed personal opinion is that they are not liable in this case since they did have a security guard, but that guard is also being sued (https://www.washingtonpost.com/news/morning-mix/wp/2018/06/0...).

Otherwise yes, it is quite possible to be liable for whatever happens on your private property. If drug deals are taking place between third parties in your house won’t you be liable? If you allowed those parties there you most definitely will be.

You're still punting the ethical question to a question of law. If someone is on your property and a car off the street swerves into your property and kills them surely you wouldn't be liable... or let's say a meteor hits your guest. Surely there is a limit to where liability kicks in. Where should that limit be and why

If your business is in letting the cars swerve onto your driveway then you will be liable. Don’t compare normal and regular human behavior on a platform to a meteor hitting the guests.