Jackson's sister, singer Janet Jackson, had her own concert troubles after suffering from a rare form of migraine headache, the singer told the entertainment TV show "The Insider." The headaches led the singer to postpone dates on her "Rock Witchu" tour last year.
When a performer does pull out of a show, he or she often is able to find an amicable resolution with the promoters by re-scheduling the concert, said Jerry Mickelson, the owner of Chicago-based Jam Productions.
"If the performer didn't show up, they'll typically make it up," Mickelson said. "It's a business -- they can't afford to cancel. They need the money just like anybody else."
Jackson, however, had a poor history of reconciling with promoters -- when he cancelled shows, he often wound up in court. In 1993, promoter Marcel Avram, the owner of Munich-based Mama Concert, sued Jackson for $20 million for cancelling his "Dangerous" world tour. The suit alleged that the singer hid an addiction to morphine and Demerol.
The following year, a Chilean promotions company sued Jackson for $5 million for canceling two concerts, one in Chile and another in Peru. The company said Jackson cancelled because of a "back ache" but a lawyer for the company told the media that they didn't believe the excuse.
In 2000, Avram took Jackson to court again, this time suing the pop star for $21.2 million for pulling out of two New Year's Eve concerts. Those cancelled concerts, Avram alleged, left him $11 million in the red and resulted in another $10 million in lost profits.
But such a litigious history and Jackson's reported health problems weren't enough to scare off AEG. Concert organizers told ABC News they believed Jackson was ready for the 50-show run, especially given the careful way this particular concert series was organized.
"We are talking about 50 shows in one city, no travel and living in a beautiful estate in London," AEG Live CEO Randy Phillips said. "He was going to average two and a quarter shows a week."
Limiting the stress on Jackson's schedule was one of many, some would say, extraordinary precautions AEG took to make sure its star was stage-ready. At the pop star's request, AEG paid for Jackson's personal cardiologist to accompany him in London.
Jackson "looked me in the eye [and said], 'Look, this is the machine,' pointing to his body. 'This is the machine, that fuels this entire business, OK? ... I need a doctor 24/7,'" Phillips told ABC News.
Organizers also monitored Jackson's eating habits.
Choreographer Kenny Ortega "would cut his chicken breast and feed him," Phillips said. " ...In the last week, I brought in someone whose sole purpose was to remind him to eat. That was my biggest concern, was his weight."
To further safeguard its investment in Jackson, AEG took out multiple insurance policies on the shows and was able to secure $25 million in insurance coverage through Lloyd's of London, a highly-placed source within the insurance industry told ABC News.
Experts say that while promoters may be loathe to shell out money to buy insurance for smaller acts, it's not unusual for promoters to buy cancellation and "non-appearance" insurance -- which specifically protects against a performer's absence -- for major stars. That, after all, is when millions of dollars are at stake.
Cancellation and non-appearance insurance can run tens of thousands of dollars per show, Moody said.