We have a multi insurance model in part because Obama adopted the Massachusetts model developed by Romney. I don't know the thinking behind it, but it made some sense in that it would be more acceptable to Republican voters having been developed by an R governor. The GOP made Romney disavow it.
Other countries offer efficient and cost-effective health care without all the American amenities. NPR did a story a very long time ago on how it was cheaper to get an operation in Belgium, but "colder" on the customer experience side.
Right now HHS is not interested in cost-effective ways to manage health care. If they were, they'd be more for making vaccinations accessible to people who want them. A vaccination is a lot cheaper than an emergency room/treatment visit for RSV, measles, flu, Covid, polio, etc.
I would think insurance companies would push for more vaccination access, since it helps their bottom line. Both flu and Covid viruses can revive cancer cases, which are expensive to cover. And RFK Jr. + DOGE have made cancer even harder to treat.
Just fixing priorities would be a big step forward at this point...and getting HHS to promote cost-effective health measures.