Medicaid has legal acceptance requirements that other insurance does not. I believe large hospitals in particular have to accept Medicaid because they lose other government subsidies if they don’t. In many ways Medicaid is the “best insurance that money can’t buy”.
Also, even small business employees can pay for health insurance with pre-tax dollars, although it may need to be claimed on a tax return.
Lastly, if a medical treatment is FDA approved and medically necessary typically a plan must cover it, or propose an equivalent treatment (i.e. generics)
The plan cannot prescribe a specific treatment regimen, although they can make reimbursement of one treatment contingent on trying something else (usually much cheaper option) first, as long as there isn’t a medical reason not to do so.
Medicaid pays providers less than Medicare because, politically, the population that needs Medicaid (poor people) does not have the political power that Medicare (old people) does.
By paying providers less, there is less incentive to see Medicaid patients, and it effectively limits the amount of healthcare poorer people receive. However, the convoluted nature of the process gives politicians plausibly deniability, since people generally do not understand how care is being rationed.
Similarly, employees of large businesses get access to health insurance at pre tax prices, while employees of small businesses do not since businesses with less than 50 employees are not required to offer employer subsidized health insurance.
ACA did greatly assist with the price transparency by standardizing what health insurance has to cover though, and by creating healthcare.gov, so we are moving in the right direction.
However, the other end of this is that the government uses managed care organizations (MCOs, health insurers), to ration care by having different rules for approving who gets what care. For example, the government pays for both Medicaid and Medicare. But Medicaid is via state governments’, and each state will hire a certain MCO to implement the Medicaid plan’s rules for that state.
And the rules of that plan will state patient has to follow so and so healthcare regimen to get X treatment, and so doctors have to follow that specific course of treatment in order to get paid for that patient. So the state will have different rules for the Medicaid patient (more strict, less reimbursement) than the federal government will for Medicare and Tricare patients (less strict, more reimbursement.
Meanwhile, people will bitch at MCOs (insurers) not approving payment or doctors will complain about having to get pre authorizations for providing healthcare, when in reality, the rules are not being made by insurers, but rather by the government themselves who then contract with MCOs to implement those rules, and take the heat from the public for doing so.