Now... yes, in an imaginary world where handwavium drone-robots make it possible to deliver anything you want for free and never mind the logistical implausibilities

Drones aren't very implausible tech. Amazon is already in field trials to deliever packages via drones.

*Although even then you still need room for customization- a pizza place that literally refuses to make pizzas with more than one topping combination will usually lose out to a pizza place that lets you pick your toppings.

It's not that simple. At the highest price points restaurants don't let you order your toppings. The extend to which people value customization has a lot to do with the culture.