6 years ago 90,000 were running on bunker fuel
370 million tonnes of it get burned every year and the price is rising
The market is not very good at correcting for the future. Regulatory pressure would be the primary mechanism for change.
But again, if Apple wanted to be more regulated they wouldn't be manufacturing in China.
And while I'm all for regulation, I'm basically pessimistic. Then again, overpopulation and nuclear escalation turned out less bad than I expected, so what do I know?