Maybe they are testing new printing techniques on the $5 bill that might go into the next redesign of the $100 bill.
Why do people still use cash?
Debit cards and credit cards, folks.
Almost all banks cover all illegal charges if you report in a timely manner.
Instant, crystal clear records on your computer.
Almost no risk for robbery, except from a few morons like the Homocide Twins in Chapel Hill who posed for ATM photos.