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.