Why don't we ask air travelers to choose their meal in advance? [closed]

Some airlines do ask travellers what they want to eat in advance. However it typically only occurs in premium cabins.

Singapore airlines has Book the Cook

Reserve your main course up to 24 hours before your flight from a wide selection of meals, including creations inspired by our International Culinary Panel. We offer 'Book the Cook' service in Suites, First Class and Business Class. We also offer 'Premium Economy Book the Cook' service in Premium Economy Class.

BA lets you choose your meal in advance in Premium Economy and above:

Choose your meal in advance

On selected flights you can choose your main meal from the on-board menu between 30 days and 24 hours before your flight, for no extra charge.

Economy passengers on BA can choose (and pay for of course!)

Order your main meal in advance

For more choice and peace of mind, you can choose and purchase your in-flight meal from our exclusive online menu between 30 days and 24 hours before your flight. This meal option is available on many flights departing from London Heathrow and includes drinks at no extra cost.

If you choose not to order a meal online, we will offer you a complimentary standard meal.

American airlines lets you pre-order in First or Business:

Reserve your entrée before you fly

Flying in First or Business Class? We’re the first U.S. airline to offer you the choice to reserve your entrée on American Airlines flights with scheduled meal service. To enjoy this personalized service, simply reserve your meal at least 24 hours before departure.

Similar pre-ordering is available on other airlines for premium classes. For economy passengers I believe the way of avoiding wastage is to just restrict the last few rows to whatever is left over!

As pointed out in comments, you can order a special meal in advance which might help you get a choice that suits you, and if it doesn't at least you'll usually be served first...

Most times I book a flight, I'm asked my meal preference. I always fill this in. Sadly, the airline regularly doesn't honour my request (I typically ask for an Asian Vegetarian Meal, which almost never is available and seldom defaults to a regular vegetarian meal).

If airlines would make meal selection mandatory and would honour the requests, wastage would be significantly less. The technology and systems are in place.