The way that the nonexistent tacocopter would work would be that you charge your purchase to a debit or credit card or PayPal or whatever, and tacocopter delivers the tacos. It does not take money or tips.
I find it annoying when there is a tip jar on the counter for someone who is just taking orders. In a restaurant, people do not tip the cook or the kitchen staff. They are paid by the price of the food. One should not be expected to pay extra for normal service that does not consist of more than ringing up a purchase and handing you a bag. Please.
And no, I NEVER put money in a tip jar, unless I find a penny on the floor.