The machine compares all the data collected from the front and back of the ID and the boarding pass.
A Driving License (the most common ID TSA sees for domestic flights, guessing probably 95% of ordinary pax) does
not contain a frequent flyer number, ticket number, airline name, destination, flight number, flight date, gate number, boarding time, passenger record number, elite status, cabin class or seat number.
A boarding pass does
not contain an address, photo, gender, date of birth (unless TSA starts requiring this secure fright stuff on every BP), DL number, name of state where a person's DL was issued, or categories of motor vehicles a person is authorized to operate by their license to
drive.
They say
the machines will be stand alone devices not hooked to any datbases to get and compare such info.
That leaves only the NAME to compare. First, Middle Last, perhaps in a different order on the two items.
TSA is admitting the TDCs cannot do this mentally, after reading the name off both the BP and ID, because they want to buy a machine to compare the names.
Why not just hire some TDCs who can read and process three words mentally?