...and except for the fact that the US Passport Card itself (DS-11) requires another ID card, so the same exact problems arise.

And those IDs usually require proof of residency and/or a copy of a US birth certificate, which can be problematic to acquire or prove in their own ways for the more vulnerable to disenfranchisement (such as the homeless) in our society.

Legislature may overcome that hurdle by amending the Passport Act, making the Passport Card free and internationally valid federal ID document on its own. And do not say that Birth Certificate is too costly.