>United Health Insurance has a profit cap, it’s a % of revenue. Sunshine Hospital has no cap. So Sunshine Hospital charged United Health Insurance X$ and that profit rolls up to United Health Group.

That doesn't really work as a strategy unless UHI cornered the insurance market within a given region, otherwise they'd lose business to competing hospitals. You might then say "hospitals aren't competitive, they're (regional) monopolies!", which might be true, but if that were the case, you'd expect them to raise prices anyways. They're profit maximizing companies after all, not operating out of altruism.