>>65323
>It's not much different than letting your pets roam free in the front yard.
It's completely different, because you're not letting pets roam free, but are inviting human beings who have free will and are responsible for their own actions, and in your OP, they didn't even break anything. If you create a flashmob of ten thousand people in a rural neighborhood and they set a truck on fire, then we can talk about your responsibility, but that wasn't your scenario. Your scenario was that the streets would have way too much traffic and so driving would become riskier, but no single person could be held liable for that result. So basically, you're held liable not for the actions of others, but for the aggregate result of their actions.
Again, if you invite too many people over and then they violate the NAP, we can talk about your liability for their actions. When they instead cause damage by their aggregated actions which they cannot be held responsible for, when the individual actions are all lawful, and when the property owners involved took no measures to lower the risk for themselves or those on their property (by limiting the number of drivers on the road), then I don't see strong grounds for liability. It's possible, like when you cause a stampede by not organizing a festival correctly. That happened in Germany during a Love Parade, but in that case, the visitors didn't know what was happening, while the organizers could've anticipated the stampede.