Is there any upside in keeping a physical copy of one's health insurance membership card in the United States, or is a scan of it enough? (assume the scan is backed up and it will not get lost.)
This should normally be fine, most insurance companies contracts allow you present your card in physical or digital form. Additionally there is no law requiring a physical card.
However this can fall apart in two situations, first if you are taken to ER in an ambulance, the doctors will check for your insurance card, if they do not find it you will likely receive bills yourself for the care, which you will have to retroactively sort out with the hospital and insurance company, which can be a lot of work.
Second I know some clinics whose IT systems require they scan an actual card, and may refuse to treat you or at least refuse to bill your insurance if they cannot do so.
So in summary it is not mandatory to have a physical insurance card but it can make getting care easier in some situations.
This doesn't seem particularly wise.
Although most offices/ clinics are probably capable of dealing with a scan of your health insurance card sitting on your phone, filling out paperwork is often a relatively slow process. Particularly if you're visiting a clinic/ office for the first time, the staff are likely to either hold your physical card for a number of minutes or scan the physical card so they have a hard copy they can refer to while they're filling out your paperwork. If all you have is a soft copy on your phone, that involves handing over a rather expensive piece of technology to potentially several different people each of which might get called away if they are needed for something that is higher priority (i.e. a sicker patient). That would create rather substantial risks that someone would accidentally damage your phone or intentionally steal it. That would be particularly likely if you were sick enough that you weren't able to stand and observe everyone using your phone.
Even if the office could handle a scan, many front-line customer service folks are going to be very wary about touching someone else's phone. If you're making $11 an hour, accidentally dropping a customer's $1100 phone is rather catastrophic so lots of people simply refuse to touch someone else's phone.
Practically, I'd expect it would also be a pain because something will inevitably cause the phone to stop showing the card before they were done needing it. It's easy to accidentally flip to a different picture, for example, and a phone with decent security will likely lock itself pretty quickly if you just hand it over. If someone has to pause filling out your paperwork several times to have you unlock the phone, that is almost certainly more annoying (and time consuming) than bringing a physical card would be.
If you're dealing with a smart person at the front desk and you've got relatively common insurance, they can probably copy down the numbers and additional markings that they know are needed from your scan onto a Post-It note that they can use to fill out subsequent paperwork rather than holding your phone an constantly referring back to it. If you don't have common insurance or the person at the front desk isn't familiar with all the back office stuff, however, the fact that insurance cards often have a lot more than a name and a number on them make it a pain to deal with in a non-original form which may tend to screw up your bills. For example, there may be a P in the upper right-hand corner of your card to indicate that you've got a PPO plan and some piece of billing software may ask whether that is present. If whoever copied your card information didn't make a note of that on the Post-It either because they didn't realize the significance or just overlooked it, that could snowball into the system thinking you're on a different type of plan and screwing up how you are billed. It's undoubtedly possible to fix this later but that's likely to involve a lot of time on the phone with providers and insurers that will erase any benefit you can from not lugging the tiny piece of plastic with you in the first place.
In all honesty, you don't even need a scan. A couple of key pieces of information about your coverage are sufficient.
I've worked verifying insurance coverage at a large hospital, and the idea that your insurance card is inherently valuable and useful is common. But it's not very well supported. The main thing that a health care provider uses the information on your insurance card for is quickly and easily verifying that your coverage is active.
Nothing related to insurance billing happens until that verification is complete. There will be no mistaken assumptions of coverage, policy limitations, or similar because your insurance card does not reflect that level of detail. The verified information (primarily member ID and group ID) will definitively indicate every relevant detail of your policy, and that information will be handled by the billing office.
This information can be entered after the fact, because your insurance contract covers medical services received during your coverage period. Any re-coding or billing practices will simply be updated when the insurance information is updated. None of the insurance information you provide does anything until it is verified, and the card itself (physically or as a scan) has much to do with that.
Please note: if you refuse, or otherwise fail, to provide your insurance information accurately and in a timely manner you will not be able to guarantee that the insurer can be successfully billed later, leaving yourself liable as an uninsured patient.
What you really need, at minimum, is the name of the specific insurer and your member ID. Ideally you will also have your group ID and a contact number for the insurer. Over nearly six years, literally the only thing I ever did with a patient's insurance card was use it to contact the insurer (via phone or online interface) to verify active coverage. And even then, I nearly always just copied the relevant information into my notes-- I almost never took possession of the card beyond that.
The verification of insurance will also address any particular features your coverage may have such as service exclusions or carve-outs, network restrictions, and so on, to the extent that the provider is willing and able to record and use that information.
The reasoning is pretty straightforward: insurance cards can be out of date or faked very easily, and no medical provider is going to take your word for it that you are covered in a way that is relevant to the visit (virtually no insured people understand the details of their policies well enough to report them meaningfully at the time of service in the first place, and it's easy to lie).
While there are edge cases, particularly around non-emergency care in a satellite clinic (as opposed to a hospital), they are relatively rare and staff absolutely will have ways to verify your coverage anyways, as long as you have the necessary information to do so. And, again, it is the verification of coverage that matters.
Clinic staff may not enjoy sitting on the phone or faxing a request for a copy of your insurance card (in the rare case they actually require that), but that has little to do with you as a patient and the problem is not avoided by the insurance card itself.
The only case I can think of where your actual insurance card is valuable is when there are multiple possible insurance offices which cannot verify coverage for other offices and you might not be sure which is the right one. The most common of those I've dealt with are any sort of Blue Cross/Blue Shield insurance (they have distinct offices for each state, which don't share that kind of information) and TriCare (there are regional offices, which do not share that kind of information).