Okay, I'm one of these people. I was assaulted when I was 16, and I have never been able to have a relationship since (now 39). I've never had consensual sex. By containing my trauma by not getting into relationships I'm a perfectly happy and normal human being - nobody knows this is behind my life choices, not even my parents. They just think I'm asexual. I'm honestly perfectly 'normal'.
For around 15 years I have absolutely desperately wanted a child. I feel bereft that I can't have one. I earn £30k, live alone in the south east (where all my family are) so there's not a lot left after housing, and not enough to raise a child on without going onto benefits.
I've accepted I can't have one by IVF. Is it fair gay couples can get help when I can't? I don't think it's fair that it's uneven, but life isn't fair, and where is the line? I say I've accepted it - to be honest, it's still fucking hard. And I really worry in a couple of years when I am literally infertile and the option is 100% gone, how I'll feel.
Any judgement about single parents I think really isn't ethical - around a third of marriages fail, more failures in unmarried couples - there's too many other factors that impact whether a family can be stable or not. And financially, plenty of people get pregnant knowing they'll need to receive benefits. What's the difference?
Really, there are no easy answers. Anyone putting a one-line opinion isn't really looking at the whole picture.