But this is the problem with capitalism and health care, the providers just stop if there's not enough money in it for them.
Is this supposed to be a flaw?
If the cost of a lab is $500/patient then the patient (or their insurance) pays the $500 and the lab exists. If the cost of the lab is $50,000,000/patient, the lab probably shouldn't be funded, because its cost/benefit ratio is very bad and the same money could have saved more lives by putting it somewhere else.
What would you do in the alternative? Have the government provide unlimited funding for things that cost more than they're worth?
The patient (or whoever is paying the bill) and the provider determines the "worth". If they can't agree on a price, then it's not worthwhile.
In communism, would you really want to extract the equivalent of $50m of labour and resources in order to provide one person with this test? I can't imagine how that would be affordable.
Putting a monetary price on it in order to quantify the cost doesn't fundamentally change the equation. In the communist utopia I imagine it would be more like forcing x architects, engineers and builders to construct the facilities for the testing, x researchers and scientists to develop and conduct the test, x caregivers, plumbers, cleaners, drivers, baristas, chefs, etc for x weeks to provide this "free" test for one individual. Is that "worth" it?
You don't need to invoke the boogeyman of "communism", in advanced developed societies there's plenty of examples of expensive treatments being provided to the edge cases of healthcare because it's such a minuscule amount of people suffering from these illnesses that on the overall scheme of things it's not a huge burden to society to allow someone to live if they have a chance.
Before you bring it up: yes, of course it's not perfect, of course some people do not get access to some treatments but it's overall a much better outcome than leaving people to fend for themselves and pay for treatments inaccessible to any non-millionaire.
If your only morality is through economic/financial terms I really invite you to question why you think that way, there are many other ways to think of trade-offs for providing access to specialty life-saving treatments even if it's at a cost to society, it just depends on what you think should be valuable. To me, life is valuable, and if a society can support giving more treatments at a loss to create less suffering it's a good society.