I definitely feel for those with peanut allergies....but I can also understand the mom with the 2yr that innocently brought along a PBJ for lunch. I'm not sure I want to listen to a hungry 2 year old for a 4 hour flight

so I would hope that the airlines start getting smart and make the announcement before people board. That mom may not be happy about having to buy more food, but it's better than having a screaming 2 year old to deal with!
Note to self.....pack some extra grapes, carrots and cheese to share with that 2 year old!
Seriously, though...I wonder WHY the airlines wouldn't announce it at the gate, repeatedly, so that people could at least make alternate arrangements. Or at the very least I wonder if they carry "safe" food on the plane at all times so that the 2yr old can at least get something to eat!
And for the person who questioned having to eat on a 4 hour flight......let me tell you our schedule....first, you have to arrive 2 hours before that 4 hour flight (and ours is actually a 4 hour 50 minute flight if it's non-stop more if it's not nonstop)....so that makes at least 7 hours (and by the way the 2 hours is not my idea, it's what our local airport posts as the time to arrive, some airports are 1 1/2 but ours is 2....at least it's down from the 2 1/2 for a year or so after 9/11). It's a 90 minute drive to the airport.....at least 15 to 30 minutes from dropping us off to standing in line to check our bags. We're at almost 9 hours now. Yes, there is food available in the airport, but it's expensive, it tasteless, and when the kids were young, well, let's just say I'd have to bring along a change of clothes, my kids were (and to some extent still are) messy eaters. I doubt most adults would be happy going 9 hours between meals....and I didn't even count the 20-30 minutes to get baggage, and time to get the rental car and then find food once we've landed. For us, travel from our front door to WDW's front door is an all day experience.
Even if you were to eat when you get through security.....6 hours is a long time for a child to go between meals. That's why elementary schools typically had snack times in addition to lunch....and then when you got home from school mom had a snack waiting for you to tide you over for dinner. I'm not saying that a child can't do it....but it's pretty tough explaining that to a toddler who isn't going to understand or care....and even a slightly older child won't be as patient when their tummy grumbles. So yes, a parent will bring food along for their child if they want to keep said child happy.....because bored children get hungrier fast too. And I'm quite sure that you'll appreciate the fact that we all keep our kids happy....because happy kids are quieter kids.
But.....I'm wondering about the people who are outraged about peanut allergies.....do you not have someone at your child's school with an allergy, or your church, or in your child's circle of friends? I homeschool my kids, so I can't speak of the school situation, but we have friends at church, support group, co-op and in the neighborhood with allergies to some or other type of nut. For that reason, PB is an "at home" only food for us. Thankfully by the time this became seemingly the norm, my kids were past the "will only eat PBJ" stage.
To some extent I just don't understand why manufacturers still produce non-peanut items in the same factory as peanut items. When it's a life or death situation for SOOOO many people, unlike a decade ago when it was rare....you'd think that it would be a marketing advantage to have a separate facility for peanut items. I know the mom's I've talked to avoid certain brands just because they have friends (or friends online) who had problems with that brand because of cross contamination. Another note to self....someday when I win the lottery and can build a factory, make it a no peanut allowed company, and make a fortune........just like the no-carb industry a few years ago!