Minifingers - Yes, that was my point too.
JCB - You have said "there is a small but very present risk that a home birth could result in a disastrous outcome that could have been avoided had delivery been in hospital. It's tiny, but it's there."
Which is fine, but yes, it is tiny. So tiny it isn't showing up in the stats in terms of outcomes for almost all groups in both home and MLU planned place of birth. It shows up a tiny, tiny amount in homebirth for first timers, but bear in mind that they lumped a lot of adverse outcomes together to give statistically significant outcomes, we aren't talking a standalone risk of neonatal death or long term damage.
Against that background, I feel it is valid to weigh in the equation that, if you choose hospital, there is a much increased chance that you will have an instrumental or surgical delivery. Along with other downsides that are more prevalent in hospital - like emotional trauma to the mother resulting from being left alone and in pain, etc. To some people those won't weigh as negatives, to others they will heavily. And these are less serious, but far higher frequency risks. You would think, as you say, that 'if you needed intervention you'd end up with it anyway' wouldn't you? But the stats don't bear that out. The stats say that, if you take a group of low risk women and some plan home/MLU and some plan CLU, the ones planning CLU are far more likely to end up with sections/intrumentals. Which implies that something in their care or setting is increasing the rates (or, to put it more emotively, that CLUs leave you exposed to instrumentals/sections which could have been avoided).
I dislike the implication (not saying you are, but which you often see in these debates) that it is only relevant to weigh the tiny, tiny (not even showing up in the stats), but obviously catastrophic risk and not the fairly high but less serious risks when making your decision. That's what we do in almost any other decision making process. Except, as you say, humans are famously bad at balancing and judging risk - hence so many people afraid of flying but few of cars.
As regards the seatbelt analogy - seatbelts do all that damage whilst saving you. I think we were talking at cross purposes. If I drive around without my seatbelt I gain nothing on an average journey, and I lose if there is an accident. The equivalent for birth would be if my seatbelt might randomly bruise me or fracture my ribs without there having been an accident.
I also disagree with the idea that a homebirth that ends in a hospital transfer is 'failed'. It isn't comparable to a car only working half the time. It's like saying that the many, many first time mums who want a natural birth and end up with an epidural are 'failed' natural births. I don't think that most people who choose home birth see it that way. They see home as where they would like to be if things are going well and they are comfortable, then hospital as the choice to move to if not. Just as many mothers who choose to labour in a CLU/alongside MLU might choose gas and air and the pool as the favoured choice, and move to further pain relief if they need it. We'd never call them 'failed', so why apply that language to a homebirth transfer when it is really just responding to changing circumstances in a responsible way?