Article 1 is about certain for profit hospitals setting quotas on the number of patients doctors admitted to the hospital, and giving kickbacks to doctors for ordering tests (which is illegal).
Article 2 is addressing a cancer treatment, not diagnostic tests. And has one quote by a doctor concerned about oncologists being pressured to use proton therapy. No mention of quotas.
Article 3 is about the proliferation of advanced diagnostic imaging (MRI, CT, etc) in private clinics and the concerns about over utilization of these diagnostic tests as well as potential conflicts of interest with doctors having a financial stake in the tests they're ordering. These are both real problems in the US medical system. However, no mention of US hospitals placing quotas on diagnostic tests ordered by doctors on their staff.
Is it possible these types of quotas have occurred? Sure. But is this typical practice in the US? No.
Your experience is different from mine. Ordering unnecessary tests is typical practice in my experience. And doctors are quick to reject tests done at another hospital, as if tests done at another hospital are untrustworthy.
Any time a US hospital has expensive equipment, doctors working at the hospital are under pressure to keep it running. You can find any number of articles on this topic if you're willing to spend a few minutes googling.
It's definitely the case that many unnecessary tests are ordered. That is a different issue from quotas, which is specifically what I was addressing.
Anyway, I will concede that my personal experience practicing medicine is not necessarily representative of the practice of medicine in all areas of the country.
Article 2 is addressing a cancer treatment, not diagnostic tests. And has one quote by a doctor concerned about oncologists being pressured to use proton therapy. No mention of quotas.
Article 3 is about the proliferation of advanced diagnostic imaging (MRI, CT, etc) in private clinics and the concerns about over utilization of these diagnostic tests as well as potential conflicts of interest with doctors having a financial stake in the tests they're ordering. These are both real problems in the US medical system. However, no mention of US hospitals placing quotas on diagnostic tests ordered by doctors on their staff.
Is it possible these types of quotas have occurred? Sure. But is this typical practice in the US? No.