I just made a TPE-HKG trip 2 days ago on CX.

Just a quick run-down on the checks:

- Check-in counter to obtain boarding pass. Presumably this is where the mistake occurred.

- Scanning boarding pass prior to security: All they did was take my boarding pass. Scanning it will essentially show the SAME details of the boarding pass on their computer screen and also a indication of whether it is valid. Presumably it would NOT allow for the same boarding pass to be scanned twice. But for this lady, she did have a valid boarding pass so no issues there.

- Exit control through immigration - I had to present my passport. Did not specifically ask for my boarding pass although I presented it anyways. I presume there is not an absolute need to present a boarding pass, esp. if you are a Taiwan citizen as it would be a similar to Hong Kong citizens through HK borders. As long as she carried valid documents, she is free to go. I also did not notice whether or not there are automatic gates that she may have gone through.

- Boarding at gate - ground agents DID NOT check my passport. All they did was scanned my boarding pass and off I went. So again very plausible that this incident happened.

So I guess the bucks stop with CX and ONLY CX with the way that TPE currently operates.