The 'retail' prices doctors and healthcare providers charge patients are effectively secret until after care has been given. However, for the overwhelming majority of medical goods and services provided, medical billing departments know precisely (or can provide an excellent estimate of) the cost.
The agreement to buy most medicine is inherently coercive because a person is faced with trading money to stop the suffering and/or death of themself or someone they love.
It is the role of government to insure that medical billing departments do not intentionally or unintentionally overcharge patents who have agreed to purchase medicine while in a implicitly coercive situation.
The first and foremost step in accomplishing this goal is to require medical prices to be transparently available.