Total population (341M) is the wrong divisor. It’s so much worse.

Count the number of Americans who would have an ID worth scanning (aka ages 18 or over): 269M [1].

Or the number of Americans with a driver’s license: 212M (2013) [2].

1: https://www2.census.gov/programs-surveys/popest/tables/2020-...

2: https://www.bts.gov/content/licensed-drivers