I've given this subject a lot of thought. Although all airlines around the world are guilty, I tend to believe US airlines are more guilty than most.
I'm a frequent long-haul flier, sitting in business or "clase primera" for 10 to 12 hours from take off to landing. I include this information not to brag, but to note that at my age I tend to freeze up and stay in the same position for several hours after a flight of more than 5 hours. Age is a bitch. On long-hauls the planes are outfitted with sleeping quarters for both the cockpit personnel and the attendants. Granted, it's usually just a fold down bed with a curtain at the front or back of the plane, but they do afford pilots time for catching a few hours of sleep.
There is also a BIG difference between flying a domestic US carrier and an International carrier. I've got enough Delta Sky Miles to ignore the constantly changing fly miles rules. However, I'll fly Delta LAST if there is no LAN Chile, British Airways, Gull, or Aeromexico/Mexicana flights available.
As for the USA's treatment of medical students, interns, and those doing residencies -- well, it's much different for medical students in most EU countries, Mexico, and South America. In many cases the academic bar is higher (this told to me by my Argentina-trained urologist in Buenos Aires who did a three-year stint at a Mayo clinic in Minnesota before he spent an additional four years of post doctoral at Pierre and Marie Curie University in Paris). All physicians work long hours, but the USA has a medical training system inherited and modeled after the needs of fixing up broken meat for the Civil and subsequent foreign wars. In short, a heart surgeon in Johannesburg, South Africa (home of the first heart transplant), will probably have had more sleep than the chest cracker working for Humana or Kaiser Permanente.
But back to feeling secure about who is in the cock pit of a passenger plane. The airlines I mentioned earlier have not followed the cost-cutting measures that Delta/Northwest have implemented; specifically, cutting the cock pit crew down to two, making the co-pilot also play navigator or gopher.
And if anyone recalls, even though the Air France/British Airways Concorde service was never a money maker, it was finally put out of service because a USA Continental Airline lost a small piece of "ad hoc" repair metal from near its cowling. The "fine" job of the Continental mechanics fell off on the tarmac where it punctured the tire of a Concorde taking off and sending a plane load of Germans to their death.
Aerolineas Argenntina is famous for having the "oldest" fleet of jets of any world airline. However, the company bought its long-haul equipment new back in the 1970s and inherited "new" equipment when Southern Winds, a private venture underwritten by the Argentine government, went belly up after it was discovered the heads of Southern Winds had been using the airline to move loads of cocaine. Over time, those new Southern Winds jets had their livery colors painted to match the Aerolineas Argentina fleet. Despite flying 747s that were new in 1970, Argentina's signature airline has one of the best air safety records in the world. But the government of Argentina recognizes that the airline will probably never be profitable. However, they'd rather have a safe airline than a profitable one. Too bad they can't have both. However, it is reassuring to see their 747s visible from the road to Ezeize Airport and watch the Boeing-trained air craft mechanics keeping them in perfect working order.
When I'm in the USA, if the choice is flying United, Delta, or American Arilines . . . I increase my risk of death and dismemberment by simply driving to where I would normally fly.