All legitimate government is a mutual insurance company.
One may ask what it is legitimate for a government to insure and that is a good question but if one posits "capitalism" and does not start with property rights, what does the government insure and what is the basis for underwriting hence charging insurance premiums?
The insurance premium one pays on a property right is going to be actuarially calculated based on multiple factors, one of which is the value of the property. This is the case with _all_ property insurance. That ends up looking a lot like a flat tax on the liquidation value of net assets.