To illustrate why, consider the "value" of a (1) a toilet, (2) nuts and bolts (sorry, I'm not great at examples). You couldn't live well without a toilet, the differential cost of having/not having a toilet in your home is immense. That doesn't mean it's reasonable to spend thousands of dollars on a single toilet -- even if you would if you absolutely had to. The cost isn't that high. The same goes for nuts and bolts in a product: they can be essential for the functioning, but it doesn't really cost much, nor makes sense to use uber-costly nuts and bolts. So a naive differential definition of value can be just a rent-extracting proposition, which I think most orgs would try to avoid.
If you're sure no one else in the world could deliver this solution (i.e. it's extremely scarce and non-reproducible), then the value proposition starts to make more sense (because your time and attention is also limited). I tend think that's rare.
So it seems more natural to adapt to each situation: you need to estimate your (operation) costs and target revenue, and then charge with a healthy margin on that; and if your service is highly unique or in high demand, you adapt by increasing your pricing accordingly.
Check out Toto washlet prices. :-) e.g. https://www.totousa.com/washlet-with-smart-toilet-g450-10-gp...
But I agree with your point. If you have some specialized, almost unique, knowledge, have plenty of demand, and are hard to substitute for--and it's something high value--you can charge a lot.
Indeed I would complete the analogy as follows: if only you could produce toilets in the entire world, you could (and probably should) charge a lot of it, since it would be so scarce -- it would be the stuff of world leaders and celebrities; or you could charge for 'how to make a toilet' (which makes sense since your production capacity is limited). That's when your product/service justifies something close to value pricing.
I don't really know why. It's partially hubris. But I think it stems from not being able to separate the superficial understanding that happens when being told something from the true understanding of synthesizing that understanding yourself. Most executives seem to go through life thinking they are amazing just because they can understand what people are telling them and attribute it to themselves, when in reality they can make nothing of value.