Thousands of jetskis are sold annually in Australia and I havent heard of a death in over 12 years in Australia.
They are like cars, motorbikes, even weekend racing cars, or go-karts,  all safe when u have safety lessons n education with responsible driving practices.

Its a rare occassion someone gets killed on one. *** It would be good to know the full circumstances.
Also, jet skis in the USA have the highest safety standards in the world, just like Australia, but accidents do happen no matter what precautions u take.

Plenty of deaths as a result of jet skis

http://www.heraldsun.com.au/news/victoria/swimmers-jet-ski-death-prompts-calls-for-tests-insurance-regulation/story-fn7x8me2-1226281817180
Melbourne 2012

http://www.heraldsun.com.au/news/victoria/tributes-flow-for-melbourne-jet-skier-killed-in-race/story-fn7x8me2-1226335909975
QLD 2012

http://www.dailytelegraph.com.au/archive/national-old/swimmer-struck-by-jet-ski-in-port-melbourne-dies-in-hospital/story-e6freuzr-1226282134436
Another Melbourne 2012

This does not include all the near misses or serious injuries which occur during the summer period either.  They just don't make the news.