Real ID validates that you are the person you are at the time of issuance, but does not guarantee that the possessor of the ID is that person. This stems from the fact that an ID is "something you have". Like any secure system, you should use multifactor authentication. The facial scan is "something you are", so the combination of ID and scan provides that. One might also use "something you know", such as your adjusted gross income (AGI) that the IRS used before.
I think the difficulty is that the (federal) government can't currently do anything except the "something you know" part. It can't use "something you have" (because too many people are opposed to federal government issued ID), and "something you are" appears beyond the scope of the federal govt to implement (correctly) at this time.
Every IRS, Social Security, DHS/CBP, and USPS branch are locations where they could proof your identity in person. It is simply a matter of will to implement the policy and enable the software features for government employees to perform the function.
I would also propose finding ways to drastically reduce the cost of issuing smart passport cards, and slowly transforming that into a national ID over time as the electorate composition changes. Your passport number eventually becomes your national ID number.
Real ID validates that you are the person you are at the time of issuance, but does not guarantee that the possessor of the ID is that person. This stems from the fact that an ID is "something you have". Like any secure system, you should use multifactor authentication. The facial scan is "something you are", so the combination of ID and scan provides that. One might also use "something you know", such as your adjusted gross income (AGI) that the IRS used before.