Shouldn't it matter to the victim?
This is an interesting essay, but I feel the lack of focus on norms and outcome probabilities is what really drives the distinction in intuition between the two cases, rather than a difference in what matters to the victim or an omission/commission distinction.
* In case 1, Maria is imminently dying and Wilfred is imminently dying. Both need to make it to the hospital to live. In the real world, this means both have a pretty good chance of dying - medical care isn't that great, there's no guarantee either will survive even if they make it. If Maria's already the one in the car, might as well be her that makes it as getting her to stop to pull over and switch out for Wilfred probably just increases the chance neither will survive on net.
* In case 2, Maria is imminently dying but Wilfred is not. Given Maria has a pretty good chance of dying soon anyway (as medical care isn't that great), but Wilfred will be fine if he can get off the road (seems eminently plausible), it seems like a bad choice from a consequentialist perspective to kill Wilfred and try and save Maria.
To reframe the case in a way that doesn't lead to such strong intuitions:
* Case A: Maria and Wilfred are both dying of thirst on an island, but know rescue is imminent in a few days. There is enough water to sustain one, but not both of them, for that time (if they split the water they will both die). Maria and Wilfred are matched in every way that would predict life expectancy. Maria already has the water bottle. I have no intuition about who should get the water, but if Maria already has it, it doesn't seem unreasonable for her to be the one to live.
* Case B: Same as Case A, but this time Wilfred has the water bottle among his possessions but hasn't realised. Maria notices, and wants to take the water bottle and drink it to survive. Again, I don't have the intuition that it is unreasonable for her to do this and be the one to live.
In general, I think what guides intuitions in these scenarios is norms and outcome probabilities sneaking in, even when we're supposed to assume these people live in a (social) frictionless vacuum with no broader consequences for society of their actions. Reframing the situation often leads to a different intuition, which implies something fishy is going on...
The problem with person-affecting views
I go back and forth between person-affecting (hedonic) consequentialism and total (hedonic) utilitarianism on about a six-monthly basis, so I sure understand what you're struggling with here.
I think there's a stronger intuition that can be made to argue for a person-affecting view though, which is that the idea of standing 'outside of the universe' and judging between world A, B & C is entirely artificial and impossible. In reality, no moral choices that impact axiological choices can be made outside of a world where agents already exist, so it's possible to question the fundamental assumption that comparisons between possible worlds is even legitimate, rather than just comparison between 'the world as it is' and 'the world as it would be if these different choices were made'. From that perspective, it's possible to imagine a world with one singular happy individual and a world with a billion happy individuals just being literally incomparable.
I ultimately don't buy this, as I do think divergence between axiology and morality is incoherent and that it is possible to compare between possible worlds. I'm just very uncomfortable with its implications of an 'obligation to procreate', but I'm less uncomfortable with that than the claim that a world with a billion happy people is incomparable to a world with a singular happy person (or indeed a world full of suffering).
on [deleted post]
I accept the first premise for the same reason as I'd accept the second premise - positive or negative wellbeing, is axiomatically, better or worse than no experience at all.
I don't need to reason as to why having happy feelings is better than feeling neutral - it just is in an immediate sense.
I struggle to understand why you don't believe that there should be symmetry for positive and negative experiences? I understand that it may be easier to achieve higher magnitude negative feelings (e.g. easier to torture someone than make them ecstatic), but given symmetric experiences why don't they have the same relevance with respect to not-existing?