Mostly the latter.
Nuclear verdicts are driving commercial insurance through the roof. Examples:
1. Company driver trainee and trainer are driving in a winter storm. Drizzle turns to freezing drizzle. Mom and kids are driving the opposite direction in a pickup, lose control, cross the median, and collide with the semi that is traveling 48 mph. Verdict for the plaintiff of $100 million, because the truck company didn't have ambient air temperature sensors/displays. Had they been available to the driver, he might have pulled over before the collision. In addition, they put a trainee on a JIT load (news flash, they are almost all JIT loads), and that means the company fostered an unsafe culture.
2. Driver goes over HOS and plows into a line of stopped traffic. He's a single owner-operator, and now deceased. Lawyers scored nuclear verdict against the company who owned the trailer and brokered out the power-only load (Owner/operator pulls their load in their trailer, only providing himself and the tractor for the specific load), because had they not contracted with this O/O, the crash wouldn't have occurred. In reality, they contracted with a broker who sold the load to the O/O who crashed. Imagine having nothing to do with a collision other than your trailer and your customer's load yet facing a $92 million verdict.
That, in a nutshell, is why commercial insurance is going sky high. The lawyers know it, that's why you see "Hit by a truck? Call Chuck!" billboards and their ilk scattered across the country. 30% + expenses on a $100 million verdict makes the lawyers rich as hell.