I agree that the challenges aren't unsurmountable, but we have to make sure that we realize everything we change has unintended and unforeseen consequences, even things that seem as simple as adding an additional click or checkmark.

You are right there are those who do not seek care because of privacy, but in my experience they are by far a minority compared to the people who don't get healthcare because there aren't enough providers to get an appointment (mostly because they are all already too busy and overwhelmed to take on new patients), are worried about cost, or who just are in denial about how sick they are.

The deal with insurance cards though is that there is no problem or issue if you don't remember to carry it. Registration can still be done, they just look you up by name, address, or SS# if needed. Not to belabor the point (because as you mention you could use a network) but any system that depends on people carrying something will have a lot of caveats.

No matter what you pick it will sometimes not work, the network will be down, the USB flash memory will no longer work, the USB port will be broken, etc... so there will have to be a non-emergency allowance for 'token' system not working. How are you going to verify it really isn't working and that people aren't just clicking 'not working' because it is easier (or because they are malicious and lying to steal data...).

With regards to automatically logging people in:
Consider your ER doctor system, ok that works when it is logged as an emergency in the ER. Now consider my role. I am a hospitalist, meaning I admit patients to the hospital and take care of the ones already admitted. Should I already be covered under the emergency since they are sick enough to be in the hospital or do I have to go through additional steps to log in to address a patient who just needs some extra nausea or pain medications or a sleeping pill? If I have to log in it detracts from the time I can spend dealing with a patient who suddenly has a more pressing issue (such as new chest pain that needs to be seen)? Of course, I am going to see the chest pain patient and so the nauseated patient is miserable for a few extra minutes. Now this sounds like squabbling over a loss of seconds but in reality managing an inpatient service is juggling multiple pages at once for sometimes several hours straight on many patients, triaging what needs to be done urgently vs later, and admitting patients, etc... It can be nonstop. So just one additional step really does add up.

So you can then say, why not have it set up that once a patient is admitted, they get logged in once and then you don't have to worry. I would then answer that that is basically what we do now. When you get admitted to the hospital you sign a release which covers this.

I will bring up another issue: you say a new provider should only have to log in once. Do you really want a provider you saw maybe 5 years ago for a one time visit have access to your records. How long until they have to reregister?

Another issue: What if you have tests done that aren't resulted by the time you leave the hospital. For example you have a blood culture that becomes positive after 5 days which means you need to be notified to get new labs done. The doctors that took care of you are off shift or on vacation. Usually this is taken care of by another provider, who you may never meet, are they going to be covered under the token system?

Out of curiosity what is your background in this since you mention User Experience?