Talk about a must-read article: Nicole Kidman's Knee - Or, how the insurance business runs Hollywood. By Edward Jay Epstein.
Since both independently financed and studio-financed movies require insurable stars, the companies that provide this coverage have immense power. By setting the premiums prohibitively high for a star who has made past claims, they can relegate a star to Hollywood's near-dead status: the uninsurables.
Providing coverage, however, is only the beginning of the insurance regimen. Insurers may require periodic medical examinations during shooting, including testing for illegal drugs, or even continuous medical treatment for some actors. (Kidman, for example, was required to take daily doses of medicine for her thyroid gland.) They also place stringent restrictions on what actors can do off the set?no motorcycles, surfing, or flying planes. As for what happens on set, the insurer analyzes every shot in the script for potential risks.
Once the production starts, they also station hawk-eyed agents, called loss-control reps, on location to make sure that the stars are not put in harm's way. If a shot presents the slightest danger of causing an injury that might delay shooting, the reps bar actors from participating in them. Either a stunt person substitutes for the actor or the shot is changed to eliminate the danger.
Goes on to discuss the claim that Angelina Jolie did "all her own stunts" in the Tomb Raider movies (she did all her own stunts that the insurance company allowed her to do while wrapped in bubble wrap).
Basically the insurance companies can sink an actor's career, they can stop a movie being made, they can remove the director from a set, they can change how a shot is framed and recorded... in fact, they literally control the movie from start to end. Plus they make millions doing it.
No wonder hollywood movies suck.