>Leaving it up to lawsuits to enforce public safety doesn't square very well with the limited-liability corporation. Imagine ten companies engaging in dangerous shipping practices, and one of them actually having an incident. If we only fine the one that had the incident, we bankrupt it and don't recover the full public-health cost.

It's not just lawsuits which would enforce these type of public safety issues sans-FAA (or other federal organization). The private companies which are doing the shipping, in this case UPS, would have their own terms of services and contracts which would prohibit unsafe transportation of hazardous chemicals.