I don't buy the fraud argument for a second. It is much more likely that someone will use a card fraudulently when their own identity can be concealed.

Taking a commercial flight is anything but anonymous....you have to show your ID to a lot of people to prove it is actually you doing the flying. Seems pretty easy to convict someone that way.

There is an incredible amount of other purchasing being done with no face-to-face interaction. Other industries have figured out a way without having to "see" the card at their place of business. Big to this entire issue with United.