Originally Posted by RealHJ

They could easily prove it, as the records and tickets are right there. And it 99% likely comes up in a flagged report of dubious bookings for manual review anyway.

This is one of things that DL is good about, (if you are lucky to reach a good agent - or just call the CS and not the reservations number) to give you a bit of flexibility if there is "good reason" for it. Only time I had to do something like that, I had a good cause. I explained it to DL. DL notated the records not to cancel the tickets (including a waiver of the then-still-in-effect 72 hour advance award cancellation requirement, as I would only have a few hours notice at most) and all was good.

With UA, no go. I tried. Several times. Due to covid uncertainty had two different bookings, in two different continents, around the same time. Basically booking two separate trips, knowing that I'll be lucky if I can make one of the two, not knowing the future covid travel restrictions du jour in each region/country, with the intent to cancel the other one (or both) a few weeks before when there is more certainty. No UA agent or CS had a way to stop the automatic auto-cancel of the later booked ticket that happens every 24 hours at a set time. After rebooking the cancelled one a few times day in and day out, gave up, on UA FTers advice.

So, giving credit where credit is due, things like this DL is better than others about.

What you are saying would be applicable if one does a fake booking in their dog's name or something that they intend to cancel just an hour before flight, in the hopes of securing a GUC upgrade or something. Such bogus bookings could be much harder to trace, and possibly untracable. That is type of conduct that obviously is not, and should not be, condoned.