I've had doctors in the ER bill directly out of their own practice several times. Out of network, but I've had no choice in the matter except to receive treatment or refuse treatment for life-threatening conditions.
The law here has changed since then to prohibit this kind of thing, though.
In the case where an ER doctor isn’t employed by the hospital, they are likely employed by a physicians’s group. These used to be ran by physicians, but now many of them have been bought up and consolidated by private equity.
The doctors likely have very little say in the pricing.
The law here has changed since then to prohibit this kind of thing, though.