Where I think we are not in agreement the question of "who to trust" and "for what purposes".
Are you going to trust me when I tell you that I'm over 18 if I provide you with the document signed by my cousin, Honest Ahmed?
Are you going to trust me when I show you the document signed by my government?
(this is the trick question, you don't have a choice, law says you must; there's a list of who you need to trust and for what purposes; like a certificate root store in your browser)
Note that I - as opposed to the posts parent - used an official trusted CA as an example.
TLS: I see your ID with some governments signature in your hand, I trust you to be you. EUDI: I see a note you wrote and I see some signed documents that you have just been to the government brain scanner, which attests you are not faking that note, and as a nice side effect the scanner scans other things in your brain, e.g. that you watch every advert diligently, send your current location regularly to your local police office and other things.
The problem is you are not creating a government issued single purpose device but you are confiscating something many user experience as a brain extension to be under the government's control as a whole.