Originally Posted by
Liface
Drink and snack carts are:
- Physically disruptive: they block a plurality of passengers from accessing a bathroom at all times and they frequently hit passengers sitting in aisle seats
- Noisy: hearing flight attendants say the same thing to every passenger is tiring, especially if you're trying to sleep
- Distracting: if a cart is coming by, you can't concentrate on what you're doing because you know you're going to get interrupted to ask if you want something
- Wasteful: I always get a weird look every time I ask for a "water, no napkin"
With the exception of the cost of the napkins, these do not affect the airline. They only affect the comfort of the passengers, which, as I'm sure you've noticed, is not very high on the an airline's list of concerns.
Setting up a system to order drinks and snacks via IFE is probably more trouble than it's worth, and then there will be people who won't know how to use it, etc. Virgin America had such a system, but many people still placed orders verbally by flagging down a crew member.
Remember that by law, there have to be a certain number of crew members on the plane, so having them do a beverage service doesn't cost the airline anything in labor.