SFO has fingerprint machines in all lines, including the citizen lines. And in the Global Entry lines, even.

I agree with you that US citizens aren't supposed to be fingerprinted on entry, but I am absolutely unsurprised that it happens sometimes.

Every port of entry I’ve been in, they have the same setup at every booth, which definitely includes the fingerprint machines. Even Texas, though I just got waved through due to the creepy gait/face recognition thing without stopping.

Yay for our AI overlords or something?