I work for a competing company in the same space. We have found that self-serve kiosks do not cut labor. They increase throughput at peak times and, by extension, increase guest satisfaction and revenue. We often have to hire more people to keep up with increased demand, while still employing a similar number of people helping guests as were cashiers before.
Edit: Ah, Fenway is Aramark. They don't care at all about guest satisfaction. I wouldn't be surprised if they are slashing labor in self-service stands.