A "dark pattern" tricks people into doing something they normally wouldn't do. In this case, to board your flight you may verify your identity in one of two ways:

1. Present your passport

2. Use the Facial Recognition software

They are tricking people into using option 2 by not informing them of option 1.

Just like Disney World - they scan your finger print upon entry to the park. When you ask to opt out, they're like "Well you're going to need to step out of line over here and give my manager some information.."

Assuming you're not being facetious, the optional "have your facial scan data uploaded to dubious parties" choice is not presented as optional, and implied consent is the default for all fliers.

This would be similar to an "opt-out" instead of "opt-in" checkbox on a "let us harvest your data" disclaimer, except that the checkbox is at 0% opacity so you don't know it's there.

Not to mention that you usually don't know about it until you get there, so you don't have time to look up anything about it to see whether you can avoid it. I read about it after buying my last ticket and learned about the passport thing, but that was because I'm interested in what the TSA does and follow security and privacy blogs.