I'm not really sure that "expert" is objectively quantifiable. Plenty of experts have their own biases, especially when it comes to information that conflicts with positions they have long advocated for.
I'm thinking specifically here of the various stories that crop up when a grad student can't publish work that contradicts their advisor's own published work, but there are also plenty of examples in other fields as well.
At the end of the day, you have people who have either studied a thing or have direct experience working with it, and you assign them some amount of trust since they've done it more than you have. You don't need to know much about a particular sub field of biology to recognize that someone claims to have expertise in biology.
Knowing some yourself helps you see if they're making it up. Even if you don't know much, you can still pick up on whether they are open to new ideas, though.
All of this is to say that reducing "expertise" to a quantifiable binary answer is not an easy thing.
And of course asking military experts about things like if wars can be won and how is often questionable as well. Experts are often experts because they are interested in those topics, and that itself is a bias. You probably don't turn into a general because you a pacifist.
So there is already a certain selection bias in who would even become an expert and why.
I'm thinking specifically here of the various stories that crop up when a grad student can't publish work that contradicts their advisor's own published work, but there are also plenty of examples in other fields as well.
At the end of the day, you have people who have either studied a thing or have direct experience working with it, and you assign them some amount of trust since they've done it more than you have. You don't need to know much about a particular sub field of biology to recognize that someone claims to have expertise in biology.
Knowing some yourself helps you see if they're making it up. Even if you don't know much, you can still pick up on whether they are open to new ideas, though.
All of this is to say that reducing "expertise" to a quantifiable binary answer is not an easy thing.