One of my good friends is an FP who did a 1 year OB fellowship (designed for FPs, not for OBs) to get training in c-sections, forceps deliveries and other high-risk pregnancy related management. She could have gotten a job doing regular vaginal deliveries without the fellowship (this is pretty common in rural areas; she had a pretty high volume of deliveries in residency) but has a higher income by being in the c-section call pool along with other FPs with similar training and a general surgeon. If one of her partner's laboring moms needs a c-section, they contact the person on c-section call to do it. If my friend's on call for L&D, she also covers c-sections but another partner will come in to help resuscitate baby while she is doing the section. She will also do tubals at the time of c-section but does not do any other surgeries. Any high-risk stuff or VBACs get sent out 40 minutes away; there's no OB/Gyn coverage in her town. My understanding is that her practice skews younger than most of her partners given she has more young female patients and their children; this also keeps her practice pretty busy. I believe she is in a group of 10-12 FPs, and 3 of them do c-sections. A couple of the senior partners no longer do any OB.
I should also mention that all deliveries that are not planned c-sections are automatically reviewed in her hospital to verify that the management was appropriate, as are any deliveries that result in transfer of mom or baby to a higher level of care. If there's an issue with a provider's management, steps are taken to ensure patient safety/quality is maintained going forward (via education/CME), or that provider loses their L&D/C-section privileges. Obviously, every hospital will vary in how this works.