The children get to about 18 months and you really don’t want them to be only children more than the fear of childbirth. You do it for them
Lovely comment there for the increasing numbers of us who do have just the one child by choice. I guess we’re all selfish and not adequately considering our children’s needs. Especially since I had an ELCS so don’t even have the ‘excuse’ of a traumatic birth to fall back on - doubly selfish I guess. 
OP I’m sorry you had such a difficult time. Based on the experiences of friends and family it does seem that memories of a traumatic pregnancy and birth fade over time, to the extent that many of my friends with ‘bad’ births and scary conditions like placenta praevia have gone on to have another. Generally I don’t think they could explain it in a rational way; they know that the painful/frightening experience happened and could happen again, but hormones/biology kicked in and they had a strong urge for another child.
Interestingly it seems to be more the experience of the baby stage, sleep deprivation, toddler tantrums etc that has put some women in my circle off having a second, rather than the more primal stuff around pregnancy and birth - except for severe morning sickness/HG which definitely lingers in the minds of a few mums I know!
I certainly wouldn’t minimise the experiences of those women who can’t forget, or who are left with PTSD after birth. They exist, and their experiences are valid. With most things, the rational response to an exceptionally painful and traumatic experience would be not to voluntarily put yourself in that position again - but our bodies aren’t rational actors, otherwise the birth rate would be falling even more than it already is!