it wont work because of how much power states have over insurance companies.
the reason insurance is so much cheaper in some states than others... is “all” about interferance by the states themselves.
If California forces all insurance companies that sell insurance in the state to offer free maternity care for instance.. and other states dont.. then insurance will be cheaper when purchased outside of California. So on the surface it looks like you would save money if you were able to buy insurance from another state. BUT that’s assuming the state would allow you to buy such insurance!
lol
New York, for example, has long had a reputation for expensive insurance policies. But New York also has a stellar reputation for keeping insurance companies solvent through its regulatory system. You simply don't find crappy, fifth-rate insurance companies in New York like you'll often find in many states that don't regulate the insurance industry very well.
I'm sure there are plenty of New Yorkers who would love to pay Mississippi premiums for their insurance coverage ... but they'd be shocked to find that the Mississippi insurance company may be out of business by the time the New Yorker files a claim.