No this claim, just because, is not weight-bearing. Extraordinary claims require extraordinary evidence. And I don't understand the motivation to make such a tenuous link when at a bare minimum one can look up direct data like joint commision and MPSMS safety data and related publications. There is tremendous variability in serious hospital safety events inter-institution for bread and butter admissions. One can further just examine CMS and NHS data for mortality and readmission for "mundane" MI, HF, sepsis, pneumonia, respiratory failure. OB/GYN outcomes are their own thing.
The flaw in reasoning here is that quality of care and outcomes is strongly related to the simplicity of diagnosis. A further flaw is the belief that care is "commoditized". Treatment protocols vary widely across institutions and health systems, often times based on cost factors. Certain basic things can not be done at night, or even the day for fully accredited hospitals. There's a big difference somewhere with 24 hour anesthesia airway and in-house surgery and not just an intensivist "on call" 600 miles away and staff that can't even do RSI. Transfer is not always an option, there's a reason critically ill people die more frequently in the sticks. If one is admitted to a regional hospital, they are unlikely to be accepted for transfer to a safer hospital unless they truly need an intervention that absolutely cannot be provided where they are, not simply because there is better backup provider support and a higher standard of safety. They will still remain at that higher risk for sepsis, or outdated care because the community physician group doesn't keep up with guidelines, or that hospital only offers the inferior treatment (or a limited formulary) for cost-cutting reasons.
Breast cancer and most cancers are not even typical inpatient encounters. Breast cancer is generally not managed on an inpatient basis, in fact one may never even have to visit an inpatient hospital campus for breast cancer. Upgrades for cancer are usually different than acute inpatient care. Breast cancer does not usually involve abdominal, intrathoracic or orthopedic surgery. Breast cancer does not usually involve advanced interventions like endarterectomy, ECMO. Cancer is a special case. Regardless of complexity, extrapolating cancer treatment to even the most "mundane" acute inpatient or surgical care really is beyond ridiculous.
This is a complex subject and this is a silly hot take.