That has at least one fairly simple explanation: those centers only take lower acuity patients. If you're complex with a history of complications, it'll be "we'll do this one at an actual hospital".
Right, I know that surgical centers operate with a variety of important limitations (surgical centers as they exist now are not an answer to the US health spending problem, which I preemptive agree is very real). I'm just saying that they're evidence of an at least semi-functioning market; they couldn't exist without that (who would send pts to them otherwise?).
That some pieces of the healthcare market may function is something we can all probably agree on. But /u/Sparkle-san was clearly speaking about something broader than these individual exceptions from the rule.
(And even in the case of a surgical center, your decision is likely to be significantly impacted by who your insurer will agree to cover.)
(This is frequently the case for my wife.)
They may also not take Medicaid patients; my state publishes lists of ones that actually do because of this. https://www.health.ny.gov/health_care/medicaid/quality/surge...