I won't use the eID because I don't believe in its promises. I don't need a third party, which would be completely dependent on government, to put a signature on my net access.
I would even prefer the dubious service because of the relationship dynamics I mentioned. Best case is that age limits for the net should be enforced on device by parents. Problem solved, no unnecessary infrastructure needed.
Theoretically you could have anyone sign and attest to your age at any time. So maybe the government gives you an attestation of 0 at birth, with timestamp (allowing age to be calculated at any time), as part of the normal new-human bureaucracy. And/or maybe you can separately hire an accredited (co-signed?) lab to perform carbon dating on you later on :)
I totally would prefer the biopsy to a government Id. So carbon dating here I come.