Aren't the costs of the US healthcare system largely driven by the cost of the healthcare workforce - basically, not enough trained personnel leading to the abs

Aren't the costs of the US healthcare system largely driven by the cost of the healthcare workforce - basically, not enough trained personnel leading to the absence of competition, leading to doctors getting paid much more than they should? Of course it's going to be more complicated, with doctors' insurance issues and the price of meds into the mix, but still, how far does this factor goes into explaining the extraordinary cost of getting a basic treatment (let alone surgery) in the US?