But many of the things he did were dubious and ACA is a perfect example of this. It's little more than an subsidy for private insurance companies whose profits dramatically increased relatively shortly after adapting to it. Universal healthcare doesn't have to be adversarial towards private insurance, but it should not directly drive increases in profits because, especially once its mandated + subsidized, profits need to be controlled as the government is effectively guaranteeing them.
Medical loss ratios (insurers must pay a minimum percent of premium revenue on medical costs) are obviously insufficient since they do nothing to motivate lower costs. On the contrary, it directly incentivizes maximizing costs which is exactly what's happened. For one specific datum medicare administrative costs are around 2% - private insurance administrative costs start around 12%.
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Basically there is no way this was even remotely close to the most socially motivated (I don't see radical as a desirable adjective) package he could get have gotten passed. And now with the country so divided, it's unlikely we'll be getting anything better anytime in the foreseeable future, because whichever side tries to pass it will simply be opposed by the other, regardless of merit. Hopefully Mamdani isn't a complete failure, because more parties in power is perhaps one way to break the divides in society.