You realize that there is much more to roasting coffee than just heating them up to some pre-specified temperature, right?

You have your bean temperature, air temperature, and drum temperature, all of which are controlled separately. You also need to bring them up at the right speed. You also control how much you circulate the air versus venting it. And all of these things are interrelated, adjusting one will change the others. I help maintain the roaster at a small coffee company, and the head roaster likes to manually control each roast. The PLC can automate an entire roast, but since there are so many variables, he likes to run it manually.

I'm really sorry if not doing things by hand offends your artisan sensibilities. Why pick on Starbucks, though, there are plenty of coffee producers who have been roasting coffee on industrial scale for much longer than the company exist.