Coincidence does not establish correlation - - -

Let's approach this scientifically.

A key symptom of scanning damage is fogging. Exposed and processed film will have images, but the contrast will be low and there may be areas in the images that look like flare.

The symptoms you describe (clear edge imprinting, but otherwise blank film after processing) indicate that the film was never exposed.

Therefore, it seems to me that you have an exposure problem rather than an airport scanning problem. Since two film sizes, and three cameras were involved, we can rule out camera failure. The only remaining explanation is that film that was submitted for processing was never exposed.

I can easily understand how this can happen with 35mm - I've done it more than a few times myself. Exposed 35mm film is returned to its original cassette, and its easy to interchange exposed rolls with unexposed rolls, especially if the film is not rolled all the way into the cassette.

Roll film is a bit harder to understand since the act of passing it through a camera transfers it totally to a different spool. Most roll films have a distinctive "exposed" warning at the tail end, and an alert processing operator should have questioned a request to process film that didn't have this flag. However, if the operator who processed that film had not done a lot of it, it is possible that he/she wasn't aware that the roll should have had an "exposed" notation.