I’d guess because it was using fingerprints, where the parodies are pretty gruesome (hack off a finger and unlock anything that fingerprint unlocks) but had a point. More “secure” biometrics, like retina scans/voice cadence analysis, are more troublesome and require expensive-at-present hardware.

There’s also the complication of the American fetish about “ooh, anything that proves I’m me can prove to the Big Bad Gubbamint or Eeeeevil Corps that I’m HERE, and I don’t necessarily want them to know that.”