How can a barista accomodate the variance in taste of a customer when pulling an espresso shot? The barista can dial in the pressure profiling, how long to pull the shot, and the grind size. For a given batch of beans, based on the type, level of roast, and age, there likely exists a sweet spot for those parameters that most baristas would agree upon. My understanding is that this is what baristas do anyway - adjust the machine for the beans available today, and then just crank them out all day long. A super automatic (or future versions) that's dialed in daily could achieve pretty much the same thing.

AFAIK, the barista will try to pull the best espresso out of the beans that they have. I'm not sure variance in customer tastes can be accomadated at this level, beyond a ristretto or an americano.