> It’s a distinction without a difference.

That difference matters quite a bit if you're specifically arguing about how people who are going to fly get to experience said flight.

[Edit] If you don't believe that parents have as much reason to fly as anyone else I don't think there's much point to further discussion. However if you do believe it then whether or not assigned seating specifically counts as a luxury matters quite a bit.

> You have to pay for all sorts of “necessities” because you have kids - just add that to the list.

Why should we accept increasing the relative cost of having kids? That's a very good way to make having kids prohibitively expensive and part of how we've gotten to the point we're at. I'm in my late 30s and most of my friends chose not to have kids. For quite a few of those friends, they decided not to have them specifically because of how expensive it's become. You might think that's acceptable or even good, but birthrates are declining and people don't seem interested in allowing immigrants to come in and fill the void so I'm not sure what the endgame here is.