Think of it this way:
Incest is not always consensual, and incest may be intra-family molestation or sexual abuse. In those cases, certainly the "rape exceptions" cover mothers who seek to abort their unborn children.
However, incest is not always non-consensual, such as between ordinary adults who just cross a "bright line boundary" and have a sexual affair that they may or may not regret. So is this why there are so many exceptions for "non-rape incest" abortions? Why, to avoid being exposed to shame or having, for example, siblings need to co-parent their rather illicit offspring that nobody will talk about? What's unique about "non-rape incest" that it requires its own carved-out exception that is so often baked into all the laws prohibiting other kinds of abortions?