What if the mandate to buy health insurance ends up being a trapdoor to a European-style health care system? It could happen, and here’s how it would play out. Democrats, who didn’t have enough support for a single-payer plan or one run by nonprofit insurers, have cobbled together a bill that forces Americans to buy insurance. In exchange for having millions more customers, insurance companies have agreed not to fight popular provisions that bar them from rejecting customers for pre-existing conditions and suddenly dropping coverage on people who have paid their premiums.