You can live on Doritos and donuts for weeks or years. You can be an ill-informed and lazy consumer and survive. I have learned when I can substitute oil for butter without problems and when it'll cause disaster.

How many people on HN have done the reading to know when a fecal occult blood test can and can't be substituted for a colonoscopy? And those are generally tests that don't have urgency. When you're in the hospital because you've been vomiting for 6 hours and are passing out, are you going to say yes to the abdominal CT? This recently came up with a friend, who called me for advice. I was with a doctor in the moment, who said that he didn't see why it was indicated (for a host of reasons). The doc got on the phone with friend who handed the phone to the physician's assistant who was going to bring him to the CT, and argued the guy out of the CT. This took knowledge, effort, and persuasion. Who here is going to be able to self-diagnose and say, "Skip the CT -- I'll have it if X has not improved in 24 hours and Y continues to decline."

For many reasons, in the US there is a lot of "defensive medicine" practiced. The doc would rather order the CT than defend against a lawsuit, and for him/her it takes less time to order the CT when the patient rolls in than wait 24 hours while observing the patient in the hospital. But it's not actually in the patient's best interest. Our incentives are not aligned, and patients do not have the time or baseline knowledge to evaluate individual treatments.

You can live for weeks without food, it can be stored easily (unlike services which aren't stored at all), and the barrier to entry is low... Many people even have their own food gardens. It's also very amenable to nearly complete automation. Therefore food is super cheap.

Those are not required procedures, so obviously there is much more of a chance for a real market there. But you can't just compare that with e.g. ER or cancer treatment.