According to this article:
http://www.ship-technology.com/feat...ction-tech-be-fitted-on-cruise-ships-4583685/
"out of more than 22 million cruise passengers in 2014, there were 18 overboard incidents, or about one for every 1.25 million passengers."
That's a 0.00001% MOB rate.
Also according to that article, there are quite a few technical problems related to the MOB detection systems:
"the industry body listed nearly a dozen obstacles to the reliability of MOB detection systems including salt corrosion or encrustation on camera lenses, surface glare from the water, the pitch and yaw of a ship, extreme weather, vessel vibration and a continually changing horizon."
Further:
"Testing of various MOB technologies has shown an unacceptably high rate of false-positives, which can negatively affect a ship's safety culture by unnecessarily diverting the attention of crew and creating expectations of an alarm being false."
The article doesn't state what the false-positive rates are. But a false-positive rate of even 0.0001% would result in 10 times as many false positives (false MOBs) as real ones. That certainly would result in a widespread expectation that any given MOB alert is a false one. I'm going to run some numbers based on a made-up 0.0001% false positive rate:
With about 20 actual MOBs per year, a 0.0001% false positive rate would mean about 200 false MOBs per year -- or about 200 cruises every year interrupted and disrupted for false MOBs. At about 3,000 passengers per cruise ship, times 200 false MOBs =
600,000 cruise passengers having their cruises disrupted due to
false MOBs every year.
All of that, in an effort to stop drunk people from being stupid and to keep suicidal people from killing themselves.
Call me heartless, but frankly, I think sometimes we have to let Darwin do his thing.