I wrote a lot longer explanation but deleted it. Suffice it to say other systems are good enough that functionally no-one wishes they had the US system instead, and it'd sure be weird if
every single other OECD state had been relying on price controls this long if they weren't having some beneficial effect.
My short-version argument would be—and I'm a little annoyed at having to explain this, because I've been explaining it to people on the Internet for 20 damn years, it's so not-hard to find this info that it's kinda difficult not to have been exposed to it, and it seems like it should be common knowledge at this point and like some folks are going way out of their way not to understand it—that the "good effect" is precisely that the US spends 50-100% more than any of these countries, per capita, and does not smoke the rest on practically every metric, instead doing a little better in some areas, a little worse in others, middle-of-the pack on others still. It sure as hell looks like we're paying a huge premium for similar outcomes, which also explains why there aren't a lot of people in other countries begging their governments to adopt a system like ours (a fact one has to explain when cherry-picking metrics to make the US look good—OK, so why aren't others rushing to copy us? At least some of them should be, if we actually do have an unambiguously better system).
The "good effect" is that other health care systems spend far less, and also don't bankrupt people over medical bills, while achieving roughly comparable results.
If I came to you and told you I had a process to produce a Tesla knock-off that produced a car a little better in some ways, a little worse in others, but pretty damn comparable, at 50-70% of what it costs Tesla to produce a car, and then showed you dozens of factories I'd already built that were demonstrably doing exactly that, you wouldn't ask me how I was defining "good effect" when I used that to describe the results of the One Weird Trick of my process. It's obvious.
Were you not aware of the vast differences in costs & accessibility between OECD healthcare systems? By which I mostly mean between the US and everyone else.