Transparency would be far more useful if it came before the service being rendered.
Obviously there are some practical limits in exceptional cases, but I can't think of another industry that has high-price services where providing estimates isn't standard.
The problem is that in many cases, there is no way for a patient to meaningfully review options, negotiate, or even consent prior to receiving treatment. For non-elective procedures, at best it's an "under duress" sort of deal.
This is why healthcare should be provided for free at the point of service, paid for by the government. It works very, very well for many other countries. The only reason we haven't been able to make it work here is the rampant lobbying.
Obviously there are some practical limits in exceptional cases, but I can't think of another industry that has high-price services where providing estimates isn't standard.