A semi-truck accident settlement or lawsuit tends to be both larger and more complicated than the average car accident settlement. Part of the complication is around ownership of the trucks, employment status of the driver ,and the severity of the injury.
But a major part of the larger settlement amounts in commercial truck accident cases is the insurance policies, which differ from standard auto insurance not so much in substance, but in policy limits. Every state has different laws around insurance policy limits, but in general drivers of commercial semi trucks (and/or the companies that employ them), are required by law to carry insurance that will cover 2-3 times the amount of a normal personal auto insurance policy.