I'm completely unfamiliar with these, but it seems like you need to press your palm against the device, no? The doctor's office is the last place I'd want to do that.

You don't need to press your palm, you just hover it over the plate for a moment. I think the hardware is just an IR illuminator+camera.

It does seem like a technology that should have a useful niche. Unlike fingerprints you don't leave partial copies of your vein pattern on everything you touch; unlike face recognition it's an explicit act you take so it can be used for attestation-type actions (like paying). It still has all the usual disadvantages and advantages of any other biometric. Perhaps the unique niche isn't big enough to fit a new product into though.