I spent a bunch of years in labs, working for the tech companies that made the "state of the art machines" that did the actual testing. Theranos wasn't only competing with LabCorp and Quest, they were also competing with the testing machine companies like Beckman-Coulter, Roche, Siemens, Bio-Rad, and many others.
So many tests get ordered for a CMP (comprehensive metabolic panel, the most common battery of tests), that you would need like 30 finger sticks to get enough blood. Theranos never clarified if they could do 30 tests on 1 drop, or 1 test per drop. That little misdirect actually matters a lot to the patient who might have to get stuck 20+ times for all the things the doctor needs.
I'm quite familiar with the way the state of the art systems work. A modern system is already testing microliters of plasma (your blood goes through a centrifuge) per test. Comparing size of blood draws is misleading. The several tubes that get drawn are for logistical reasons that don't go away if you switch to finger-sticks. For example, the law requires that a lab keep some blood on hand for emergency re-testing if it turns out you have a critical level. Maybe a tech drops your sample. Maybe the machine has a problem right when it's doing your test (happens all the time, no reason it wouldn't happen with the Theranos instrument, had it existed). How many finger sticks are required to keep some extra on hand?
Theranos was also misleading about the test time, but that doesn't get mentioned either. They claimed 4-hour test time, but compared it to the 24-hour turn around time of a major lab like LabCorp. In reality, modern systems take 8-15 minutes for most tests, depending on what it is. Large molecules (hormones, etc) and whole-blood tests can take longer, sometimes up to 1.5 hours on older machines. Nothing approaching 4 hours, though. A 4 hours test time is atrociously long.
And after all that, you still need a doctor to look at the results. Let's say the dream happened, and we all started going to Walgreens to get Theranos tested. Even if we got 30+ tests on a single finger-stick drop, we'd still need to wait 24-72 hours for the doctor to look at the results and call us.
Maybe I'm beating a dead horse at this point, but I think from the very beginning, Theranos didn't have a serious business model. I also would like anyone on HN reading this, who's interested in the medlab space, to understand that there's a lot more going on than just testing on fingerpricks and fraud here.
If any of you out there actually do have a revolutionary one-drop testing device, don't try to partner with Walgreens and open your own labs. Just sell/lease it directly to doctors and hospitals.