In the US, if the surgery is in hospital:

- Well-regarded hospitals will vet surgeons before granting privileges.

- Average hospitals give out privileges fairly easily if there are no actions against a person's license.

- There is a "collegial" review of big screw-ups that carry major reputational risk.

- As with any fee-for-service firm, "rainmakers" are highly sought after and get away with more.

- Privileges are difficult to take away once granted. (Have stronger legal protections than academic tenure in some states.)

If the surgery is in an ambulatory surgery center or doctor's office:

Basically anything goes. Ice-pick lobotomies, tonsillectomy mills, boob job factories in strip malls....all have happened in recent US history. About as well-regulated as traveling carnivals.