Unless you can afford a $6,000+ private pet airline ticket, traveling with any pet is an arduous journey. Cats, simply because they're generally smaller and can come with you in the cabin of the plane, are generally easier, but it still adds stress and extra planning to any plane ride. You have to buy a pre-approved travel carrier (and you know each airline has different requirements), pack some litter to make a portable litter box when you can find time to let them use it, hopefully get them to eat something, and somehow find a way to keep them calm from the time you leave home to the time you arrive at your destination.
In general, I think most people choose to leave their cats at home when traveling simply for these reasons. But, there are those who insist on taking their cats with them, and for the most part, all I can say is, "More power to you." I'm always happy to see a cat in a carrier on a plane, but not if it's mine. I'm already an anxious purrson, and I'm pretty sure I would be more nervous to fly with my cats than they would be to fly themselves.
Mostly, I would want to break the rules to take my cat out of the carrier and comfort them. I wouldn't be able to resist trying to make the situation better, and one of my cats would definitely make a run for it as soon as I opened the carrier, like the cat from @islswj's post on Threads, Instagram's text-based social media platform that is similar to X.
The owner and their cat were on a United Airlines flight when their cat escaped, snuck all the way up to the front, and scratched a fellow passenger. With all the chaos that followed, the aircraft was forced to return back to the airport while the flight attendant scooped up the cat, and attempted to return it to its owner. I'm pretty sure it was just trying to sneak into first class because it wanted the tuna option for lunch.
Can't blame a kitty for trying, right?