Again - this is far too complex to "first principles" your way out of. You need to be clear who you're talking about when you talk about savings (savings to the patient?, to the private insurer?, to medicare/medicaid?,to the hospital?, to the taxpayer if it's a public health system?) and even still, it will vary massively given that much of our care is state-driven.

Your figures e.g. for a CT scan are wildly wrong if you're talking about anything government-paid. The reimbursement for a differential chest CT to the facility is closer to $150 from the government (https://www.cms.gov/medicare/physician-fee-schedule/search?Y...) but again, that varies depending on a million other things.

So making some claim like the 15% savings from an NP reimbursement is only 1% of the total cost of a visit needs a heck of a lot more specificity than your gut feeling on what things might cost.