Give your head a wobble for a minute. You aren't comparing like and like here.
How exactly would that work? You get halfway through your section, and some a doctor suddenly says why don't we sew you back up and wait for a vaginal birth because something has emerged that would make it safer 😂😂😂😂😂😂😂😂.
You aren't comparing like and like here. Planned C-sections (love them or hate them), are full of fail safes, and if anything goes wrong you've already in the right place. Yes, there can be complications, but by and large they are predictable operations.
In contrast a vaginal birth is very unpredictable. Sometimes it goes great, sometimes it goes terribly. Often it's somewhere in the middle. You can't plan for when it'll happen, or what assistance will be needed. Emergencies can and do advise which require a change of plan midway through, but it's not a two-way street. You can't have an emergency doing a C-section which then requires a vaginal birth. So you're talking absolute rubbish.
As someone that had a maternal request C-section, I was very aware that there was a small chance that I could go into very rapid labour early, and then not be enough time to give birth by section. I'd made peace with that as a small possibility, so yes, there was that degree of flexibility because there are no guarantees in childbirth.
Also, a lot of people are flexible about this. It's quite common for somebody that is veering towards a section to have one booked in, but if they go into labour first they'll give natural a go first. Or were they will try vaginal birth but have a low threshold moving to C-section. Or where someone will try a vaginal birth but C-section is to be used instead of instrumental. So yes, even those that are quite happy with a C-section. Often there is some flexibility.