Plus most patients are not qualified to make medical decisions about whether a procedure is correct.
Well, there's a couple reasons for this beyond "Well, fuck even trying to be transparent."
1.) Many physicians, nurses, etc. aren't employed directly by a hospital, but instead come in under contract as part of a physician group. Hospitals charge their own fees for use of their facilities, which are completely opaque from the physicians working there in this case, every specialty contracted by a different group handles their own billing as well - this makes it incredibly challenging to try to even get an estimate when everyone is working on their own.
2.) Medical care is more like visiting a mechanic to fix your car than it is just buying a service. Even if you could try to get a reasonable quote, complications come up, part of an encounter for "I am feeling sick" is diagnosing you in the first place which can have a lot of variety in just how much is done based on the symptoms. I can say it's gonna cost $120 for you to come into an urgent care and see a doctor, but depending on what happens it could very well cost more.
3.) Billing is separate from everything else in most cases. In the first point I mentioned I work for a billing company owned by a physician group, notice the "owned by". We aren't part of our parent company in the day-to-day, in fact we collect our own revenue and the amount of money flowing between us is very one-directional (we take our billing fee and the rest goes straight to them) - the same goes with many other aspects of our operations, there is cooperation but we're still on very different sides of the fence. With that said, our providers have very little to no insight into what we actually do, they just know we code the encounters and send out claims then collect money - some may have an idea what `R10.9` means, but most don't, or which of the ED visit codes (99281-99285) are appropriate. All of this work that goes into coding an encounter is because that is what insurance companies base their allowable charges off, and it's our job to make sure it's coded appropriately so we get appropriate compensation for the services rendered. WE handle all of this work, to the physicians it's just a black box - they treat the patient, they get paid.
If you want price transparency many things need to change in the industry.