The loophole they exploit is claiming ignorance about coverage that's not under the umbrella of your deductible.
They can do this because when they check with the plan provider they don't have to, or want to do a lengthy inquiry in relation to the patient's situation and their plan. That check is usually a 2 minutes call. So they go with a blanket scenario which is:
“A patient is here for a consultation. Based on their coverage how much can I get out of their pocket?”
That's literally the only validation they are interested in doing.
Of course, you can try to fight this, but the process for this is probably so long that it's not worth your time. So they get away with it all the time. Most people don't even want to deal with this. Going to the doctor is already stressing enough, so 75 USD less is not worth it more stress. And they do this because nobody says anything and patients don’t understand well enough their coverage. The average person hardly understands the concept of a deductible.
If people were actually fighting back this it would be harder for healthcare providers to charge fees they are not entitled to.
Healthcare in the US is one of the most exploitative and unethical industries. They don't care about the patients, they only care about their money. And I'm not talking about the nurses and doctors. Most of them are simply cogs of that system. They may have knowledge of these shady things but rarely can control them (except the ones that have private practices)
I'm talking about the organizations that insure patients and the organizations that provide healthcare. Patients are always in the middle of a constant tug between insurers and providers.
In a situation where someone has to lose something, you better believe it would be the patient.