A few thoughts...
1) I will assume Sindhiguy ordered a Halal, Hindu veg or Kosher meal. IME, meal choices are constantly missed on domestic UA flights. Better chances on international flights.
2) It's not easy to get food one can eat past the security checkpoint.
3) It's virtually impossible to find acceptable and Halal/Kosher food on the secure side of the checkpoint. Vegetarian meals are not so difficult to find but the blandness is a problem for those hailing from places like South Asia.
4) Often, there is no time to purchase food airside anyway due to delays at security or tight connections.
5) Flying into the US on a non-US carrier, one is generally well fed, but one is going to get hungry if it's a two hour interval between being fed a pre-landing snack and landing, then a four hour interval while one slogs it through immigration, baggage claim, customs, re-checking bags, passing through the TSA checkpoint and finding one's gate. THen there's another hour to board one's connecting flight, taxi out, take off and climb to the correct altitude for cabin service to begin. That's when most international passengers who have not flown much in the US get the nasty surprise - 12 fingernail sized pretzels packaged in a lovely foil bag.
6) Many times, when the purser notices my meal choice was not loaded, they apologize profusely and try to pull something together. I am perfectly happy with a fruit plate and I usually have a protein shake in my bag anyway so it's not been such a big deal for me, but for many people not being able to get the food choice right can be a real inconvenience.