Its not about frivolous lawsuits as much as defensive medicine which is the standard of care. For example if you come in to the Emergency department with a traumatic brain bleed (even a tiny spec on your scan), then you end up getting another scan at 6 hours, likely platelets since you took a baby aspirin that day, a very expensive neurosurgery evaluation, keppra for 2 weeks, and continuous monitoring, even though by all metrics you have a very benign pathology. Why? Because this is the standard of practice. Not because it makes any sense.

also, keep in mind that the factor that matters the most for practice patterns (especially defensive ones which drive up cost) is not where a doctor practices, its where a doctor trains. Since most doctors train in high risk litigation environments, and most standard of care procedures are developed with defensive practices in mind, the standard of care is high cost high utilization medicine.

Source: ER doctor