I live outside DC (Northern VA) and have at least minimal knowledge on the 3 DC hospitals referred to. When I heard GW charges more than Providence I wasn’t surprised and thought ok, I’d pay more to go to GW, too. Sibley was something of a surprise.
Geography within the city probably accounts for some of the discrepancies. Sibley is located in the ‘silk stocking district’ close to the upscale MD suburbs. It’s the type hospital where you’d choose to go for non-emergency care because of its environment. And, I would assume, a disproportionately high number of its patients have insurance and/or can make co-payments. That would not be the case at Providence which is located in a lower income section of the city. GW is in a commercial district with ever-decreasing residential areas taken over by govt/non-profits/NGOs and GW itself, but it’s often the hospital of choice for lower-income and/or uninsured patients to go for treatment.
GW is a teaching/research hospital. And, thanks to Reagan and Cheney family donations (@ $10M between them) among others, GW today is a modern, beautiful facility (when Reagan had his surgery there following the assassination attempt, it was the absolute pits). It also has a Metro stop at its front door so it’s easily accessible from any part of the city.