The rule (betteridge's law) says more about the journalists who craft headlines, than it does about news articles ending in question marks. 99% of journalists

The rule (betteridge's law) says more about the journalists who craft headlines, than it does about news articles ending in question marks. 99% of journalists using interrogative headlines are not being scrupulous, when they do so. This is especially true, if the question seems shocking, or even slightly surprising, in some way. A semi-scientific article about neutrinos doesn't carry very much emotional investment among ordinary folk.