It's a good question.
In my industry everyone knows each other (or at least of each other) and you know everyone's expertise from their backgrounds and history. But when something disastrous happens in this industry an "expert" will be quizzed by the BBC, and of course none of us have ever heard of the expert, not one. You look at their background and they've never worked in a company within the industry, never worked for the regulator, never held a post even vaguely connected to that area. There seems to be a little pool of them, no qualification, no background, no credibility, a bit of amateur journalism maybe, some very questionable self-appointed awards or titles, but nothing recognisable. If it's not an "independent expert with 20 years experience" it's a 21 year old in a suit representing a "think tank". Same qualifications.
I suspect the reason is that genuine experts don't get where they are by publicly speculating... news agencies actively want some wild guesswork early in an incident because it's far more interesting to the viewer / reader than calm, qualified analysis. Which in the early stages of anything is not likely to be remotely revealing.