Delta Airlines forces you to upgrade from Basic to Main Cabin by using a dark pattern – Misdirection. They placed a frictionless primary button that would add $26 dollars to your bill in one click.
If you want to avoid additional costs, you will have to check the “Accept Restriction” checkbox and press the “Continue with Basic” link-style button that is barely visible.
This modal creates friction that forces you to make an action for lower pay, but only one click on the biggest button on the screen adds an additional charge to your card. Classic Misdirection in action.