You are right, you cannot compare open heart screening to drug testing. Period. Two different diagnosis implications, time considerations and impact on life or death. To digress: You assume that a cath is a "must do" before bypass. Sorry but you'd kill a lot of patients with that silly point of view. Things like an EKG and blood SCREENING/level tests can be done before the need to cath. If the symptoms, EKG and blood work aligns, the cath is often bypassed. A better knowledge of medicine prior to pulling out more unrelated analogies might help.
"They are not the ones that are going to have to discharge a 80 year old women for SCREENING positive for THC when she actually was just taking a proton pump inhibitor for her gastric reflux." Once again, there is NO "have to" in this scenario. Nothing dictates the "have to" you describe. Not the government, insurance companies or more importantly, good standards and practices. It is the clinicians job to discover PPI utilization and rule out cross reactivity, not a labs. If medical decisions to keep that patient is made with a legitimate purpose, acting in the usual course of medical practice, and taking reasonable efforts to prevent abuse and diversion are done, the clinician is covered.
Insurance companies and the government do know the difference between test formats. That is why different codes are used and have been changing. They also have discovered that certain companies have been overdoing it. That has been the negative impact on healthcare. I have never stated that screening is better but pointed out that confirmation is not "required" for every patient. "At least 5 confirms" for every patient is certainly not needed.