safety on shore excursions zip lines, & stingrays etc...

Regarding ziplines. I myself have no desire to do this but one of my friends did it in Mexico and boy did the contraption look flimsy! She also did it in Alaska where the equipment was much better, the US has higher safety standards then many other countries. Having just read about the fatal zipline death of an NCL cruiser I was wondering your thoughts on this subject. I also wonder if the ships will still offer this excursion as I know it is very popular. Also I realize stingray stings or deaths are pretty rare but they do occur, the sting rays maybe very tame such as sting ray city Grand Cayman, or Shark Ray alley in Belize where I snorkled with them but they do happen what are your thoughts about this. To me the sheer volume of people doing these excursion at a place like stingray city makes me feel accidents are more likely. Carnival cancelled their excursion to Shark Ray alley I heard that was a liabilty problem meaning someone sued or tried to sue in regards to some kind of accident. So I wonder what makes cruise lines decide which excursions to keep and which to scrap.