Have you noticed the tendency among some in government (looking at you, Mr. President) to order one group of people to pay for something on behalf of another group, and then to go around referring to that thing as "free"?
Ordering health insurance companies to provide contraception - or any other service - without direct charge does not make that service "free." It still must be paid for. And it makes no sense to say "the big insurance companies" pay for it. The costs are incorporated into the companies' only source of funding: the premiums paid by their customers.