You realize someone is printing the exact same amount of cards and why do you care what it costs Carnival,? Do you even know how many people are involved in the card printing process?
It's very simple. On the first day on the ship, walk over to the restaurant and ask. The host will tell you how to do it. If they can accommodate you, they will...
Is the wait time really any different? People start lining up a half for dinner at least 30 minutes early for set dining times. Then you have sit them all down at almost the exact same time. I can walk in to my time at almost anytime I want or check in 10 minutes before my table and will be notified when my table is ready.
Nobody cares. I bet there is not one person here posting here about how they noticed any difference. Most normal people are just excited to be on board and don't care about getting their keys. Isn't it funny how all companies get their passengers on before the ship leaves. Must be magic. Every line is different. Oooh a novel concept
Princess has you checkin by alphabet and the keys were literally ten feet away. It does little to slow you down at all. This is a big much a do about nothing
And you do their job? You just added another task for them. Ever think about that? If it doesn't add to their workload, the same can be applied to the check in🤔
More efficient? You now have a few thousand on board biy drinks without the card. Now look at the extra work a bartender has. You are just passing the time into someone else