Guest,
Your HR person is wrong about the insurance company setting the premiums as they are set up. When I worked for an HMO the rates were negotiated with the individual companies, they got a say in what rates their employees pay, they would say so much for singles, married couples and children. They also got a say in what kind of coverage they offered, such as birth control, IVF or mental health benefits.
Even though I worked for the HMO we did have to pay a portion of the monthly premium, however they charged us per person rather than single or family rates. They only people that got a break were the hourly people who were the majority of employees. I think they paid $10.00 less per paycheck, that break was absorbed by the salaried employees, since we were paid much more than the hourly people.