Correct. There are exceptions to this rule. Christian Care Medishare is probably one of the largest "not insurance" insurance-like financial products in the United States. But they rely on a specific faith-based exemption to legally operate.
Even with this exemption however there has been some question as to the groups legal basis to operate within every state in the US:
"In 2002, Christian Care's Medi-Share bill-sharing program was challenged by some states’ insurance regulators due to its status as a Christian healthcare organization. 43 states have inquired about the legality of the program, and in some cases legal action was taken. A series of court cases in Kentucky resulted from the specific way in which Medi-Share processed members’ shares and disbursed payments. Changes have since been made to the Medi-Share system to bring it into line with state regulations and to maintain the organization's non-insurance status. As of June 25, 2013, the court ruled that Medi-Share was allowed to operate in Kentucky. Medi-Share operates legally in 50 states with state disclosures specific to Illinois, Kansas, Kentucky, Maine, Maryland, Missouri, Pennsylvania, Texas, and Wisconsin."